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.

A223909 Numbers for which the maximal run of 1's in their binary representation contains odd number of 1's.

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%I A223909 #12 Jan 12 2014 15:36:30
%S A223909 1,2,4,5,7,8,9,10,14,16,17,18,20,21,23,28,29,31,32,33,34,36,37,39,40,
%T A223909 41,42,46,55,56,57,58,59,62,64,65,66,68,69,71,72,73,74,78,80,81,82,84,
%U A223909 85,87,92,93,95,103,110,112,113,114,115,116,117,118,119,124
%N A223909 Numbers for which the maximal run of 1's in their binary representation contains odd number of 1's.
%C A223909 We call these numbers "maxodious".
%C A223909 If a(n) is in the sequence, then 2^k*a(n) is in the sequence. If a(n)==0 (mod 4) is in the sequence, then a(n)+1 is in the sequence. If a(n)==0 (mod 8) is in the sequence, then a(n)+1, a(n)+2 are in the sequence.
%H A223909 Peter J. C. Moses, <a href="/A223909/b223909.txt">Table of n, a(n) for n = 1..10000</a>
%F A223909 Numbers n such that A038374(n) is odd. - _Charles R Greathouse IV_, Jan 12 2014
%t A223909 Select[Range[500],OddQ[Max[Map[Count[#,1]&,Split[IntegerDigits[#,2]]]]]&] (* _Peter J. C. Moses_, Mar 29 2013 *)
%o A223909 (PARI) A038374(n)=n>>=valuation(n,2);if(n<2,return(n)); my(e=valuation(n+1,2)); max(e, A038374(n>>e))
%o A223909 is(n)=A038374(n)%2 \\ _Charles R Greathouse IV_, Jan 12 2014
%Y A223909 Cf. A000069, A001969, A038374.
%K A223909 nonn,base
%O A223909 1,2
%A A223909 _Vladimir Shevelev_, Mar 29 2013