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 A171147 #5 Jul 22 2025 07:31:14
%S A171147 1,1,1,1,6,1,1,7,7,1,1,20,102,20,1,1,21,122,122,21,1,1,42,591,2828,
%T A171147 591,42,1,1,43,633,3419,3419,633,43,1,1,72,1948,23544,108870,23544,
%U A171147 1948,72,1,1,73,2020,25492,132414,132414,25492,2020,73,1,1,110,4845,106920
%N A171147 The sequence of coefficients of a polynomial recursion: p(x,n)=If[Mod[n, 2] == 0, (x + 1)*p(x, n - 1), (x^2 + (2*n)*x + 1)^Floor[n/2]].
%C A171147 Row sums are:
%C A171147 {1, 2, 8, 16, 144, 288, 4096, 8192, 160000, 320000, 7962624, 15925248...}.
%F A171147 p(x,n)=If[Mod[n, 2] == 0, (x + 1)*p(x, n - 1), (x^2 + (2*n)*x + 1)^Floor[n/2]]
%e A171147 {1},
%e A171147 {1, 1},
%e A171147 {1, 6, 1},
%e A171147 {1, 7, 7, 1},
%e A171147 {1, 20, 102, 20, 1},
%e A171147 {1, 21, 122, 122, 21, 1},
%e A171147 {1, 42, 591, 2828, 591, 42, 1},
%e A171147 {1, 43, 633, 3419, 3419, 633, 43, 1},
%e A171147 {1, 72, 1948, 23544, 108870, 23544, 1948, 72, 1},
%e A171147 {1, 73, 2020, 25492, 132414, 132414, 25492, 2020, 73, 1},
%e A171147 {1, 110, 4845, 106920, 1185810, 5367252, 1185810, 106920, 4845, 110, 1},
%e A171147 {1, 111, 4955, 111765, 1292730, 6553062, 6553062, 1292730, 111765, 4955, 111, 1}
%t A171147 Clear[p, n, x, a]
%t A171147 p[x, 1] := 1;
%t A171147 p[x_, n_] := p[x, n] = If[Mod[n, 2] == 0, (x + 1)*p[x, n - 1], (x^2 + (2*n)*x + 1)^Floor[n/2]];
%t A171147 a = Table[CoefficientList[p[x, n], x], {n, 1, 12}];
%t A171147 Flatten[a]
%Y A171147 Cf. A051159 , A169623, A007318, A171142, A171143
%K A171147 nonn,tabl
%O A171147 1,5
%A A171147 _Roger L. Bagula_ and _Gary W. Adamson_, Dec 04 2009