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 A123880 #2 Mar 30 2012 18:59:18 %S A123880 1,0,1,1,0,1,1,3,0,1,5,3,5,0,1,11,18,5,7,0,1,41,39,35,7,9,0,1,120,157, %T A123880 75,56,9,11,0,1,421,459,325,119,81,11,13,0,1,1381,1668,950,553,171, %U A123880 110,13,15,0,1,4840 %N A123880 Inverse of number triangle A123878. %C A123880 First column is A055113. Row sums are A000108. %e A123880 Number triangle begins %e A123880 1, %e A123880 0, 1, %e A123880 1, 0, 1, %e A123880 1, 3, 0, 1, %e A123880 5, 3, 5, 0, 1, %e A123880 11, 18, 5, 7, 0, 1, %e A123880 41, 39, 35, 7, 9, 0, 1, %e A123880 120, 157, 75, 56, 9, 11, 0, 1 %K A123880 nonn,tabl %O A123880 0,8 %A A123880 _Paul Barry_, Oct 16 2006