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 A143969 #2 Mar 30 2012 17:25:32 %S A143969 1,5,1,5,5,6,5,5,30,16,5,5,30,80,56,5,5,30,80,280,176,5,5,30,80,280, %T A143969 880,1856,5,5,30,80,280,880,9280,6016,5,5,30,80,280,880,9280,30080, %U A143969 19456 %N A143969 Eigentriangle by rows, n terms of (5 * A084057) followed by A084057(n). %C A143969 Right border = A084057: (1, 1, 6, 16, 56, 176,...). Row sums = (1, 6, 16, 56,...) = INVERT transform of (1, 5, 5, 5,...). Sum of n-th row terms = rightmost term of next row. %F A143969 Eigentriangle by rows, n terms of (5 * A084057) followed by A084057(n). %e A143969 First few rows of the triangle = %e A143969 1; %e A143969 5, 1; %e A143969 5, 5, 6; %e A143969 5, 5, 30, 16; %e A143969 5, 5, 30, 80, 56; %e A143969 5, 5, 30, 80, 280, 176; %e A143969 5, 5, 30, 80, 280, 880, 1856; %e A143969 ... %Y A143969 A084057 %K A143969 nonn,tabl %O A143969 0,2 %A A143969 _Gary W. Adamson_, Sep 06 2008