Ok, so the pi-day is up and running (March 14, i.e., 3-14). At approximately half past three today, some kind of pi would be served around the globe.

In an older post I found some alternative pi days for those who don’t like the date-system (Month-Day):

https://mixedsignal.wordpress.com/2013/07/04/heads-up/

and we found July 19 and July 22 as more “accurate” days for the pi – at least for us in Europe. The latter internationally acknowledged as the “Pi approximation day”. (Americans might claim March 1 as an approximation according to the principle Month/Day.)

So what else do we have? Is this it? Are there no other fancy constants that we could appreciate throughout the year?

Of course there is… forza some python and loop over the most commonly (according to Wikipedia) used constants. Standard integers aside. A euro-date below is “Day/Month” and a US-date is a “Month/Day”. I have found the best-matching date in a least-square sense.

Notice the possible benefits of celebrating some/most constants twice a year if using both Euro and US date formats! I’ve however given preference to as early dates as possible for constants approximating to the same value for several dates. For example the interesting Legendre’s constant (= 1) which could be celebrated quite a few times throughout the year, but let’s stick to January 1.

It is also worth noticing that the Feigenbaum constant approximation day could be celebrated today instead of pi.

- Btw – what else than celebrating the imaginary number i on
**February 30**.

Euro | US | Value | Constant |
---|---|---|---|

22/07 | 03/01 | 3.14159265359 | The pi day |

19/07 | 11/04 | 2.71828182846 | Eulers day |

17/12 | 07/05 | 1.41421356237 | Pythagoras day |

19/11 | 12/07 | 1.73205080757 | Theodorus day |

20/09 | 09/04 | 2.2360679775 | sqrt5-day |

04/07 | 11/19 | 0.577215664902 | Euler-Mascheroni constant |

13/08 | 08/05 | 1.61803398875 | Golden ratio |

03/11 | 06/23 | 0.261497212848 | Meissel-Mertens constant |

02/07 | 07/25 | 0.280169499024 | Bernsteins constant |

03/10 | 07/23 | 0.303663002899 | Gauss-Kuzmin-Wirsing constant |

04/11 | 06/17 | 0.353236371855 | Hafner-Sarnak-McCurley constant |

01/02 | 01/02 | 0.5 | Landaus constant |

04/07 | 04/07 | 0.56714329041 | Omega constant |

05/08 | 05/08 | 0.624329988544 | Golomb-Dickman constant |

07/11 | 09/14 | 0.6434105462 | Cahens constant |

02/03 | 02/03 | 0.660161815847 | Twin prime constant |

02/03 | 02/03 | 0.662743419349 | Laplace limit |

07/10 | 07/10 | 0.70258 | Embree-Trefethen constant |

07/09 | 10/13 | 0.764223653589 | Landau-Ramanujan constant |

09/11 | 09/11 | 0.8093940205 | Alladi-Grinstead constant |

07/08 | 07/08 | 0.87058838 | Bruns constant for prime quadruplets |

11/12 | 11/12 | 0.915965594177 | Catalans constant |

01/01 | 01/01 | 1 | Legendres constant |

11/10 | 11/10 | 1.0986858055 | Lengyels constant |

09/08 | 09/08 | 1.13198824 | Viswanaths constant |

06/05 | 06/05 | 1.20205690316 | Aperys constant |

13/10 | 09/07 | 1.30357726903 | Conways constant |

13/10 | 09/07 | 1.30637788386 | Mills constant |

04/03 | 04/03 | 1.32471795724 | Plastic constant |

16/11 | 10/07 | 1.45136923488 | Ramanujan-Soldner constant |

16/11 | 10/07 | 1.45607494858 | Backhouses constant |

16/11 | 03/02 | 1.4670780794 | Porters constant |

17/11 | 11/07 | 1.5396007178 | Liebs squareice constant |

08/05 | 08/05 | 1.60669515242 | Erdos-Borwein constant |

17/10 | 12/07 | 1.70521114011 | Nivens constant |

19/10 | 11/06 | 1.9021605831 | Bruns constant for twin primes |

23/10 | 07/03 | 2.29558714939 | Universal parabolic constant |

05/02 | 05/02 | 2.5029078751 | Feigenbaum constant |

31/12 | 08/03 | 2.58498175958 | Sierpinskis constant |

27/10 | 08/03 | 2.68545200107 | Khinchins constant |

14/05 | 11/04 | 2.80777024203 | Fransen-Robinson constant |

23/07 | 10/03 | 3.27582291872 | Levys constant |

27/08 | 10/03 | 3.35988566624 | Reciprocal Fibonacci constant |

14/03 |
09/02 | 4.6692016091 | Feigenbaum constant |

30/2 | 2/30 | i, sqrt(-1) | The imaginary day (30/2!) |