This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A090651 #8 Oct 12 2012 14:38:23 %S A090651 3,4,5,13,1,2,3,11,6,7,1,9,4,5,6,14,2,3,4,12,7,1,2,10,5,6,7,8,3,4,5, %T A090651 13,1,2,3,11,6,7,1,9,4,5,6,14,2,3,4,12,7,1,2,10,5,6,7,8,3,4,5,13,1,2, %U A090651 3,11,6,7,1,9,4,5,6,14,2,3,4,12,7,1,2,10,5,6,7,8,3,4,5,13,1,2,3,11,6,7,1,9,4 %N A090651 Perpetual calendar sequence: There are 14 basic year calendars, 7 for normal years and 7 for leap years. This sequence identifies the calendars for years 1901 through 2099, when it reinitializes because 2100 is not a leap year. %C A090651 2000 was a leap year, so no reinitializing was needed. %C A090651 Calendars are continuous so they roll from Dec 31 to Jan 01. The intercalation of the leap years causes the unusual sequence. %C A090651 a(n) = 1 for years starting on a Sunday, 2 for years starting on a Monday, so on to 7; 8 for leap years starting on a Sunday, 9 for leap years starting on Monday, so on to 14. - _Alonso del Arte_, Nov 02 2004 %D A090651 World Almanac 2003, Perpetual calendar on pages 647-648. %H A090651 <a href="/index/Ca#calendar">Index entries for sequences related to calendars</a> %e A090651 a(2003) = 4 because 2003 is a year starting on a Wednesday. %e A090651 a(2004) = 5 because 2004 is a leap year starting on a Thursday. %K A090651 nonn %O A090651 1901,1 %A A090651 Brendan Sullivan (bsulliva(AT)austarnet.com.au), Dec 13 2003 %E A090651 More terms from _Ray Chandler_, Dec 23 2003