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 A187006 #14 Feb 01 2025 14:58:46
%S A187006 1,2,6,29,202,1880,22108,315784,5322126,103541022,2285965792,
%T A187006 56501970700,1546339364952,46433615292128,1518172222889000,
%U A187006 53695946069029290,2042960241832903824,83207255745283689726,3612360848988984098484,166537270023045091100852,8125771150231992039148508
%N A187006 A diagonal of triangle A187005.
%C A187006 Definition of triangle: A187005(n,k) = [y^k] R_{n-1}(y+y^2) for k=1..n where R_n(y) is the n-th row polynomial for n>1 with R_1(y)=y.
%o A187006 (PARI) {a(n)=local(Rn=y);for(m=1,n+1,Rn=subst(truncate(Rn),y,y+y^2+y*O(y^m)));polcoeff(Rn,n,y)}
%Y A187006 Cf. A187005, A135081, A187007, A187008, A187009.
%K A187006 nonn
%O A187006 1,2
%A A187006 _Paul D. Hanna_, Mar 02 2011
%E A187006 More terms from _Michel Marcus_, Feb 01 2025