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 A172040 #9 Oct 12 2024 02:02:47
%S A172040 1,0,2,0,2,4,0,6,8,8,0,22,28,24,16,0,90,112,96,64,32,0,394,484,416,
%T A172040 288,160,64,0,1806,2200,1896,1344,800,384,128,0,8558,10364,8952,6448,
%U A172040 4000,2112,896,256,0,41586,50144,43392,31616,20160,11264,5376,2048,512,0
%N A172040 Triangle T(n,k), read by rows, given by [0,1,2,1,2,1,2,1,2,1,2,...] DELTA [2,0,0,0,0,0,0,0,0,...] where DELTA is the operator defined in A084938.
%C A172040 Riordan array (1, 2x*f(x)) where f(x) is the g.f. of A001003. Riordan production matrix is : (0, (2-x)/(1-x)).
%F A172040 Sum_{k=0..n} T(n,k) = A006318(n).
%e A172040 Triangle begins:
%e A172040 1 ;
%e A172040 0,2 ;
%e A172040 0,2,4 ;
%e A172040 0,6,8,8 ;
%e A172040 0,22,28,24,16 ; ...
%Y A172040 Cf. A104219, A108891.
%K A172040 nonn,tabl
%O A172040 0,3
%A A172040 _Philippe Deléham_, Jan 23 2010