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 A373933 #16 Jun 24 2024 05:40:11
%S A373933 1,2,3,4,5,6,8,17,54,175,506,1299,3017,6465,13021,25142,47651,91104,
%T A373933 180254,374077,810381,1800140,4019204,8888489,19322901,41223071,
%U A373933 86520282,179574728,370946309,767426451,1597653852,3354537225,7101005320,15118658953
%N A373933 Number of compositions of 7*n-1 into parts 6 and 7.
%H A373933 <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (7,-21,35,-35,21,-6,1).
%F A373933 a(n) = A017847(7*n-1).
%F A373933 a(n) = Sum_{k=0..floor(n/6)} binomial(n+k,n-1-6*k).
%F A373933 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 A373933 G.f.: x*(1-x)^5/((1-x)^7 - x^6).
%F A373933 a(n) = A373934(n+1)-A373934(n). - _R. J. Mathar_, Jun 24 2024
%o A373933 (PARI) a(n) = sum(k=0, n\6, binomial(n+k, n-1-6*k));
%Y A373933 Cf. A369809, A373912, A373934, A373935, A373936, A373937.
%Y A373933 Cf. A017847, A369849.
%K A373933 nonn,easy
%O A373933 1,2
%A A373933 _Seiichi Manyama_, Jun 23 2024