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 A152504 #11 Jul 16 2020 06:24:37
%S A152504 0,3,140,5175,183000,6416875,224662500,7863609375,275228750000,
%T A152504 9633019921875,337155773437500,11800452490234375,413015839453125000,
%U A152504 14455554393310546875,505944403833007812500,17708054134515380859375,619781894709960937500000,21692366314858856201171875
%N A152504 1/10 of the number of permutations of 4 indistinguishable copies of 1..n with exactly 2 local maxima.
%H A152504 Andrew Howroyd, <a href="/A152504/b152504.txt">Table of n, a(n) for n = 1..200</a>
%H A152504 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (45,-375,875).
%F A152504 a(n) = (11*35^(n-1) - 11*5^(n-1) - 12*(n-1)*5^(n-1))/90. - _Andrew Howroyd_, May 10 2020
%F A152504 From _Colin Barker_, Jul 16 2020: (Start)
%F A152504 G.f.: x^2*(3 + 5*x) / ((1 - 5*x)^2*(1 - 35*x)).
%F A152504 a(n) = 45*a(n-1) - 375*a(n-2) + 875*a(n-3) for n>3.
%F A152504 (End)
%o A152504 (PARI) a(n) = {(11*35^(n-1) - 11*5^(n-1) - 12*(n-1)*5^(n-1))/90} \\ _Andrew Howroyd_, May 10 2020
%o A152504 (PARI) concat(0, Vec(x^2*(3 + 5*x) / ((1 - 5*x)^2*(1 - 35*x)) + O(x^20))) \\ _Colin Barker_, Jul 16 2020
%Y A152504 Cf. A152494, A334773.
%K A152504 nonn,easy
%O A152504 1,2
%A A152504 _R. H. Hardin_, Dec 06 2008
%E A152504 Terms a(9) and beyond from _Andrew Howroyd_, May 10 2020