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 A181415 #10 May 17 2016 08:31:41
%S A181415 1,1,1,1,6,2,1,12,9,36,6,1,20,40,120,180,240,24,1,30,75,50,300,1200,
%T A181415 300,1200,2700,1800,120,1,42,126,210,630,3150,2100,3150,4200,25200,
%U A181415 12600,12600,37800,15120,720,1,56,196,392,245,1176,7056,11760,8820,11760,11760,88200
%N A181415 Irregular triangle a(n,k) = A049009(n,k)/n, read by rows 1<=k<=A000041(n).
%F A181415 Sum_{k=1.. A000041(n)} a(n,k) = A000169(n). (Row sums)
%F A181415 a(n,k) = A098546(n,k) *A049019(n,k) /n. - Compare with the formula in A101818.
%e A181415 Row three is calculated as follows:
%e A181415 ( 3 18 6) divided by (3 3 3) yielding (1 6 2)
%e A181415 1;
%e A181415 1,1;
%e A181415 1,6,2;
%e A181415 1,12,9,36,6;
%e A181415 1,20,40,120,180,240,24;
%e A181415 1,30,75,50,300,1200,300,1200,2700,1800,120;
%e A181415 1,42,126,210,630,3150,2100,3150,4200,25200,12600,12600,37800,15120,720;
%Y A181415 Cf. A000169 (row sums), A000081 (unlabeled rooted trees) A179438 (a similar refinement), A054589, A135278, A019538, A101817, A101818
%K A181415 nonn,tabf
%O A181415 1,5
%A A181415 _Alford Arnold_, Oct 20 2010
%E A181415 Edited by _R. J. Mathar_, May 17 2016