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 A219865 #12 Apr 16 2013 12:43:48 %S A219865 0,0,0,1,0,2,2,3,1,5,7,10,11,14,23,33,44,54,81,114,158,212,287,407, %T A219865 565,777,1050,1471,2036,2813,3863,5310,7370,10183,14046,19296,26726, %U A219865 36909,50955,70251,96867,133886,184841,255092,351673 %N A219865 First differences of A219795. %C A219865 2,2,3, 5,7,10,11, 23,33,44, 81,114,158,212, 407,565,777, 1471,2036,2813,3863, 7370,10183,14046, 26726,36909,50955,70251, is a subsequence of A219795(n). %C A219865 Consider A219795(n) and its successive differences: %C A219865 2, 2, 2, 2, 3, 3, 5, 7, 10, 11, 16, 23, 33, 44; A219795(n) %C A219865 0, 0, 0, 1, 0, 2, 2, 3, 1, 5, 7, 10, 11, 14; a(n) %C A219865 0, 0, 1, -1, 2, 0, 1, -2, 4, 2, 3, 1, 3, 9; %C A219865 0, 1, -2, 3, -2, 1, -3, 6, -2, 1, -2, 2, 6, 1; %F A219865 a(n) = A219795(n+1) - A219795(n). %p A219865 A219865 := proc(n) %p A219865 A219795(n+1)-A219795(n) ; %p A219865 end proc: # _R. J. Mathar_, Jan 06 2013 %K A219865 nonn,less %O A219865 0,6 %A A219865 _Paul Curtz_, Nov 30 2012