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 A322803 #6 Dec 28 2018 20:35:50 %S A322803 1,1,1,1,1,1,1,1,2,3,4,5,6,7,8,9,11,14,18,23,29,36,45,55,67,82,101, %T A322803 125,155,192,239,297,368,455,562,694,857,1058,1308,1619,2005,2483, %U A322803 3074,3805,4708,5822,7198,8900,11007,13616,16846,20845,25795,31918,39489 %N A322803 Number of compositions (ordered partitions) of n into centered heptagonal numbers (A069099). %H A322803 Wikipedia, <a href="https://en.wikipedia.org/wiki/Centered_heptagonal_number">Centered heptagonal number</a> %H A322803 <a href="/index/Com#comp">Index entries for sequences related to compositions</a> %F A322803 G.f.: 1/(1 - Sum_{k>=0} x^(7*k*(k+1)/2+1)). %p A322803 h:= proc(n) option remember; `if`(n<1, 0, (t-> %p A322803 `if`((7*(t-1)*t+2)/2>n, t-1, t))(1+h(n-1))) %p A322803 end: %p A322803 a:= proc(n) option remember; `if`(n=0, 1, %p A322803 add(a(n-(7*(i-1)*i+2)/2), i=1..h(n))) %p A322803 end: %p A322803 seq(a(n), n=0..60); # _Alois P. Heinz_, Dec 28 2018 %t A322803 nmax = 54; CoefficientList[Series[1/(1 - Sum[x^(7 k (k + 1)/2 + 1), {k, 0, nmax}]), {x, 0, nmax}], x] %Y A322803 Cf. A069099, A280863, A282502, A282504, A322799, A322801, A322802. %K A322803 nonn %O A322803 0,9 %A A322803 _Ilya Gutkovskiy_, Dec 26 2018