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 A013616 #24 Jul 24 2015 18:53:46
%S A013616 1,1,9,1,18,81,1,27,243,729,1,36,486,2916,6561,1,45,810,7290,32805,
%T A013616 59049,1,54,1215,14580,98415,354294,531441,1,63,1701,25515,229635,
%U A013616 1240029,3720087,4782969,1,72,2268,40824,459270,3306744,14880348,38263752,43046721
%N A013616 Triangle of coefficients in expansion of (1+9x)^n.
%C A013616 T(n,k) equals the number of n-length words on {0,1,...,9} having n-k zeros. - _Milan Janjic_, Jul 24 2015
%F A013616 G.f.: 1 / (1 - x(1+9y)).
%F A013616 T(n,k) = 9^k*C(n,k) = Sum_{i=n-k..n} C(i,n-k)*C(n,i)*8^(n-i). Row sums are 10^n = A011557(n). - _Mircea Merca_, Apr 28 2012
%p A013616 T:= n-> (p-> seq(coeff(p, x, k), k=0..n))((1+9*x)^n):
%p A013616 seq(T(n), n=0..10); # _Alois P. Heinz_, Jun 10 2014
%K A013616 tabl,nonn,easy
%O A013616 0,3
%A A013616 _N. J. A. Sloane_