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 A013615 #18 Jul 08 2025 02:48:30
%S A013615 1,1,8,1,16,64,1,24,192,512,1,32,384,2048,4096,1,40,640,5120,20480,
%T A013615 32768,1,48,960,10240,61440,196608,262144,1,56,1344,17920,143360,
%U A013615 688128,1835008,2097152,1,64,1792,28672,286720,1835008,7340032,16777216,16777216
%N A013615 Triangle of coefficients in expansion of (1+8x)^n.
%C A013615 T(n,k) equals the number of n-length words on {0,1,...,8} having n-k zeros. - _Milan Janjic_, Jul 24 2015
%F A013615 G.f.: 1 / [1 - x(1+8y)].
%F A013615 T(n,k) = 8^k*C(n,k) = Sum_{i=n-k..n} C(i,n-k)*C(n,i)*7^(n-i). Row sums are 9^n = A001019. - _Mircea Merca_, Apr 28 2012
%p A013615 T:= n-> (p-> seq(coeff(p, x, k), k=0..n))((1+8*x)^n):
%p A013615 seq(T(n), n=0..10); # _Alois P. Heinz_, Jul 25 2015
%K A013615 tabl,nonn,easy
%O A013615 0,3
%A A013615 _N. J. A. Sloane_