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 A099175 #19 Sep 09 2023 11:34:36
%S A099175 1,8,176,92576,25710762176,1983129874961075240576,
%T A099175 11798412302889389755255045998938726679954176,
%U A099175 417607598606915139792416465578985202696175989567316713156694229302007260054247019608576
%N A099175 a(1) = 1, a(2) = 8; for n > 2: a(n) = a(n-1)*(3*a(n-1)-2).
%C A099175 n*(3n-2) is the n-th octagonal number (A000567).
%F A099175 a(n) = (A003487(n-1)+1)/3 for n >= 2. - _Ondrej Kutal_, Sep 08 2023
%t A099175 Join[{1}, NestList[ #*(3*# - 2) &, 8, 7]]
%Y A099175 Cf. A000567, A003487.
%K A099175 nonn
%O A099175 1,2
%A A099175 _Jonathan Vos Post_, Nov 15 2004
%E A099175 Edited by _Stefan Steinerberger_, Jul 25 2007