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 A373935 #13 Jun 24 2024 05:43:14
%S A373935 0,0,1,4,10,20,35,56,85,131,231,506,1287,3367,8464,20026,44609,94334,
%T A373935 191710,380190,748924,1491735,3044927,6398259,13770795,30031820,
%U A373935 65615746,142422743,305750022,648652029,1362500345,2843775112,5922703731,12356169575
%N A373935 Number of compositions of 7*n-3 into parts 6 and 7.
%H A373935 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (7,-21,35,-35,21,-6,1).
%F A373935 a(n) = A017847(7*n-3).
%F A373935 a(n) = Sum_{k=0..floor(n/6)} binomial(n+k,n-3-6*k).
%F A373935 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 A373935 G.f.: x^3*(1-x)^3/((1-x)^7 - x^6).
%F A373935 a(n) = A373936(n+1)-A373936(n). - _R. J. Mathar_, Jun 24 2024
%o A373935 (PARI) a(n) = sum(k=0, n\6, binomial(n+k, n-3-6*k));
%Y A373935 Cf. A369809, A373912, A373933, A373934, A373936, A373937.
%Y A373935 Cf. A017847.
%K A373935 nonn,easy
%O A373935 1,4
%A A373935 _Seiichi Manyama_, Jun 23 2024