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 A373912 #14 Jun 22 2024 14:11:38
%S A373912 1,1,1,1,1,1,2,9,37,121,331,793,1718,3448,6556,12121,22509,43453,
%T A373912 89150,193823,436304,989759,2219064,4869285,10434412,21900170,
%U A373912 45297211,93054446,191371581,396480142,830227401,1756883373,3746468095,8017653633,17151612398
%N A373912 Number of compositions of 7*n into parts 6 and 7.
%H A373912 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (7,-21,35,-35,21,-6,1).
%F A373912 a(n) = A017847(7*n).
%F A373912 a(n) = Sum_{k=0..floor(n/6)} binomial(n+k,n-6*k).
%F A373912 a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 6*a(n-6) + a(n-7).
%F A373912 G.f.: 1/(1 - x - x^6/(1 - x)^6).
%o A373912 (PARI) a(n) = sum(k=0, n\6, binomial(n+k, n-6*k));
%Y A373912 Cf. A373907, A373908, A373909, A373910, A373911.
%Y A373912 Cf. A099099, A099131, A107025, A373913.
%Y A373912 Cf. A017847.
%K A373912 nonn,easy
%O A373912 0,7
%A A373912 _Seiichi Manyama_, Jun 22 2024