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 A373910 #11 Jun 22 2024 14:11:46
%S A373910 1,1,1,1,2,9,37,121,332,808,1837,4113,9497,23091,58462,150129,382810,
%T A373910 960520,2373982,5816480,14230964,34948927,86295036,213973997,
%U A373910 531470618,1319411997,3270186871,8091796123,20002405065,49435009494,122222402392,302354237393
%N A373910 Number of compositions of 7*n into parts 4 and 7.
%H A373910 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (7,-21,35,-34,21,-7,1).
%F A373910 a(n) = A369815(7*n).
%F A373910 a(n) = Sum_{k=0..floor(n/4)} binomial(n+3*k,n-4*k).
%F A373910 a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 34*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7).
%F A373910 G.f.: 1/(1 - x - x^4/(1 - x)^6).
%o A373910 (PARI) a(n) = sum(k=0, n\4, binomial(n+3*k, n-4*k));
%Y A373910 Cf. A373907, A373908, A373909, A373911, A373912.
%Y A373910 Cf. A369815.
%K A373910 nonn,easy
%O A373910 0,5
%A A373910 _Seiichi Manyama_, Jun 22 2024