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 A251704 #24 Mar 28 2025 10:24:45
%S A251704 1,1,0,1,3,5,9,18,35,67,129,249,480,925,1783,3437,6625,12770,24615,
%T A251704 47447,91457,176289,339808,655001,1262555,2433653,4691017,9042226,
%U A251704 17429451,33596347,64759041,124827065,240611904,463794357,893992367,1723225693
%N A251704 4-step Fibonacci sequence starting with 1, 1, 0, 1.
%H A251704 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (1,1,1,1).
%F A251704 a(n+4) = a(n) + a(n+1) + a(n+2) + a(n+3).
%F A251704 G.f.: (1+x)*(x^2+x-1)/(-1+x+x^2+x^3+x^4) . - _R. J. Mathar_, Mar 28 2025
%F A251704 a(n) = A001630(n-2)+A001630(n-1), n>2. - _R. J. Mathar_, Mar 28 2025
%t A251704 LinearRecurrence[Table[1, {4}], {1, 1, 0, 1}, 36] (* _Michael De Vlieger_, Dec 09 2014 *)
%o A251704 (J) NB. see A251655 for the program and apply it to 1,1,0,1.
%Y A251704 Other 4-step Fibonacci sequences are A000078, A000288, A001630, A001631, A001648, A073817, A100532, A251654, A251655, A251656, A251703, A251705.
%K A251704 nonn,easy
%O A251704 0,5
%A A251704 _Arie Bos_, Dec 07 2014