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 A029640 #15 Mar 02 2020 07:27:23 %S A029640 2,2,2,4,2,2,6,14,16,2,20,30,2,8,50,36,2,2,10,44,112,182,196,140,64,2, %T A029640 54,156,294,378,336,204,2,12,210,450,672,714,540,100,2,660,1122,1386, %U A029640 1254,2,14,90,352,1782,2508,2640,1210,506,144,2,104,442,4290,5148,1716,650,2,16 %N A029640 Even numbers in the (1,2)-Pascal triangle A029635. %K A029640 nonn %O A029640 1,1 %A A029640 _Mohammad K. Azarian_ %E A029640 More terms from _David W. Wilson_ %E A029640 Leading 2 inserted as consequence of change in A029635 by _Sean A. Irvine_, Mar 01 2020