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 A087736 #10 Sep 08 2013 13:30:13 %S A087736 1,0,1,0,1,4,0,4,23,34,0,34,249,606,496,0,496,4354,14181,20434,11056, %T A087736 0,11056,112238,450097,894838,885032,349504,0,349504,4008024,18911670, %U A087736 47136095,65613780,48468804,14873104 %N A087736 Triangle T(n,k) read by rows given by [0, 1, 3, 6, 10, 15, 21, ...] DELTA [1, 3, 6, 10, 15, 21, 28,...] where DELTA is the operator defined in A084938. %F A087736 Sum_{k, 0<=k<=n}T(n,k)*x^(n-k)=A000012(n), A011782(n), A001147(n), A002105(n+1), A000364(n), A126151(n), A126156(n) for n = -3,-2,-1,0,1,2,3 respectively . %e A087736 Triangle begins: %e A087736 1; %e A087736 0, 1; %e A087736 0, 1, 4; %e A087736 0, 4, 23, 34; %e A087736 0, 34, 249, 606, 496; %e A087736 0, 496, 4354, 14181, 20434, 11056; %e A087736 0, 11056, 112238, 450097, 894838, 885032, 349504; %e A087736 0, 349504, 4008024, 18911670, 47136095, 65613780, 48468804, 14873104 ;... %Y A087736 Diagonals give A002105: [1, 1, 4, 34, 496, ...] Row sums give A000364 : [1, 1, 5, 61, 1385, ...] Euler numbers. %Y A087736 Cf. A000217 A000384 A002105 A084938. %K A087736 easy,nonn,tabl %O A087736 0,6 %A A087736 _Philippe Deléham_, Sep 30 2003, Jul 17 2007 %E A087736 Corrected and edited. - _Philippe Deléham_, Nov 24 2008