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 A013618 #26 Aug 16 2023 08:19:18
%S A013618 1,1,11,1,22,121,1,33,363,1331,1,44,726,5324,14641,1,55,1210,13310,
%T A013618 73205,161051,1,66,1815,26620,219615,966306,1771561,1,77,2541,46585,
%U A013618 512435,3382071,12400927,19487171,1,88,3388,74536,1024870,9018856,49603708,155897368,214358881
%N A013618 Triangle of coefficients in expansion of (1+11x)^n.
%C A013618 T(n,k) equals the number of n-length words on {0,1,...,11} having n-k zeros. - _Milan Janjic_, Jul 24 2015
%H A013618 Seiichi Manyama, <a href="/A013618/b013618.txt">Rows n = 0..139, flattened</a>
%F A013618 G.f.: 1 / (1 - x(1+11y)).
%F A013618 T(n,k) = 11^k*C(n,k) = Sum_{i=n-k..n} C(i,n-k)*C(n,i)*10^(n-i). Row sums are 12^n = A001021. - _Mircea Merca_, Apr 28 2012
%p A013618 T:= n-> (p-> seq(coeff(p, x, k), k=0..n))((1+11*x)^n):
%p A013618 seq(T(n), n=0..10); # _Alois P. Heinz_, Jul 24 2015
%Y A013618 Cf. A001020 (right edge).
%K A013618 tabl,nonn,easy
%O A013618 0,3
%A A013618 _N. J. A. Sloane_