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.

A043688 a(n) = (s(n)-1)/2, where s(n) is the n-th number whose base-2 representation has exactly 5 runs.

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%I A043688 #16 Apr 13 2021 23:10:11
%S A043688 10,18,20,21,22,26,34,36,37,38,40,41,43,44,45,46,50,52,53,54,58,66,68,
%T A043688 69,70,72,73,75,76,77,78,80,81,83,87,88,89,91,92,93,94,98,100,101,102,
%U A043688 104,105,107,108,109,110,114,116,117,118,122
%N A043688 a(n) = (s(n)-1)/2, where s(n) is the n-th number whose base-2 representation has exactly 5 runs.
%C A043688 a(n) = A238247(n) - 1. - _Reinhard Zumkeller_, Feb 20 2014
%H A043688 Vincenzo Librandi, <a href="/A043688/b043688.txt">Table of n, a(n) for n = 1..1000</a>
%t A043688 (#-1)/2&/@Select[Range[400],Length[Split[IntegerDigits[#,2]]]==5&] (* _Harvey P. Dale_, Oct 04 2013 *)
%Y A043688 Cf. A238247.
%K A043688 nonn,base
%O A043688 1,1
%A A043688 _Clark Kimberling_