cp's OEIS Frontend

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.

A272851 Number of distinct nonzero Fibonacci numbers among the contiguous substrings of the binary digits of n.

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%I A272851 #25 Nov 08 2016 21:03:53
%S A272851 1,2,2,2,3,3,2,3,2,3,4,3,5,3,2,3,3,2,3,3,4,4,4,4,3,5,5,3,5,3,2,3,3,4,
%T A272851 4,2,3,3,3,4,3,4,5,4,5,4,4,4,4,3,3,5,6,5,6,4,3,5,5,3,5,3,2,3,3,3,4,4,
%U A272851 5,4,4,3,2,3,4,3,5,3,3,4
%N A272851 Number of distinct nonzero Fibonacci numbers among the contiguous substrings of the binary digits of n.
%H A272851 Marko Riedel, <a href="/A272851/a272851.maple.txt">Maple program to compute sequence.</a>
%e A272851 a(53) = 6 because 53=(110101)_2 which contains (1)_2 = 1, (10)_2 = 2, (11)_2 = 3, (101)_2 = 5, (1101)_2 = 13 and (10101)_2 = 21. The one digit only contributes once.
%t A272851 s = Fibonacci@ Range@ 30; Table[Length@ Select[Union@ Flatten@ Function[k, Map[FromDigits[#, 2] & /@ Partition[k, #, 1] &, Range@ Length@ k]]@IntegerDigits[#, 2] &@ n, MemberQ[s, #] &], {n, 120}] (* _Michael De Vlieger_, May 08 2016 *)
%o A272851 (PARI) isfib(n) = my(k=n^2); k+=(k+1)<<2; issquare(k) || (n>0 && issquare(k-8)) ;
%o A272851 a(n) = {vb = binary(n); vf = []; for (i=1, #vb, for (j=1, #vb - i + 1, pvb = vector(j, k, vb[i+k-1]); f = subst(Pol(pvb), x, 2); if (f && isfib(f), vf = Set(concat(vf, f))););); #vf;} \\ _Michel Marcus_, May 08 2016
%Y A272851 Cf. A000045, A078822, A272852, A272886.
%K A272851 nonn,base
%O A272851 1,2
%A A272851 _Marko Riedel_, May 07 2016