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 A013617 #21 Jul 24 2015 19:05:45
%S A013617 1,1,10,1,20,100,1,30,300,1000,1,40,600,4000,10000,1,50,1000,10000,
%T A013617 50000,100000,1,60,1500,20000,150000,600000,1000000,1,70,2100,35000,
%U A013617 350000,2100000,7000000,10000000,1,80,2800,56000,700000,5600000,28000000,80000000,100000000
%N A013617 Triangle of coefficients in expansion of (1+10x)^n.
%C A013617 T(n,k) equals the number of n-length words on {0,1,...,10} having n-k zeros. - _Milan Janjic_, Jul 24 2015
%F A013617 G.f.: 1 / (1 - x(1+10y)).
%F A013617 T(n,k) = 10^k*C(n,k) = Sum_{i=n-k..n} C(i,n-k)*C(n,i)*9^(n-i). Row sums are 11^n = A001020. - _Mircea Merca_, Apr 28 2012
%p A013617 T:= n-> (p-> seq(coeff(p, x, k), k=0..n))((1+10*x)^n):
%p A013617 seq(T(n), n=0..10); # _Alois P. Heinz_, Jul 24 2015
%K A013617 tabl,nonn,easy
%O A013617 0,3
%A A013617 _N. J. A. Sloane_