%I #15 Oct 25 2019 04:55:34
%S 1,14,331,12284,663061,49164554,4798037791,596372040824,
%T 91991577140521,17244625801225094,3861296322290987251,
%U 1017889493782391701364,312043142223584185393981,110072908401904868672053634
%N Third column of triangle A060074.
%C Also third diagonal of triangle A060058.
%C a(n) is n-fold iterated sum of squares with last upper summation index 3 and other upper summation indices j[k]+1, k=2,...,n. See Comments A060061 for the threefold iteration with last upper summation index n.
%F a(n) = A060074(n+2, 2) = A060058(2+n, n).
%F a(n) = (1/4)*(A000364(n+1) - A000364(n)). - _Benoit Cloitre_, Apr 06 2003
%F G.f.: sin(x)^2/cos(x)^3 = x^2/2! + 14*x^4/4! + 331*x^6/6! + .... - _Peter Bala_, Oct 22 2019
%Y Cf. A000364.
%K nonn,easy
%O 0,2
%A _Wolfdieter Lang_, Mar 16 2001