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 A373907 #12 Jun 22 2024 14:11:59
%S A373907 1,2,10,53,264,1294,6349,31200,153366,753836,3705166,18211117,
%T A373907 89508951,439943336,2162355196,10628140702,52238121106,256754344524,
%U A373907 1261967164192,6202664757387,30486569842400,149843813435961,736493759087077,3619922936674360
%N A373907 Number of compositions of 7*n into parts 1 and 7.
%H A373907 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (8,-21,35,-35,21,-7,1).
%F A373907 a(n) = A005709(7*n).
%F A373907 a(n) = Sum_{k=0..n} binomial(n+6*k,n-k).
%F A373907 a(n) = 8*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7).
%F A373907 G.f.: 1/(1 - x - x/(1 - x)^6).
%o A373907 (PARI) a(n) = sum(k=0, n, binomial(n+6*k, n-k));
%Y A373907 Cf. A373908, A373909, A373910, A373911, A373912.
%Y A373907 Cf. A005709, A369836.
%K A373907 nonn,easy
%O A373907 0,2
%A A373907 _Seiichi Manyama_, Jun 22 2024