A117890 Numbers k such that number of non-leading 0's in binary representation of k divides k.
2, 4, 5, 6, 10, 11, 12, 13, 14, 16, 18, 22, 23, 24, 26, 27, 28, 29, 30, 36, 40, 42, 46, 47, 48, 54, 55, 58, 59, 60, 61, 62, 65, 75, 76, 78, 80, 84, 88, 90, 94, 95, 99, 100, 102, 104, 105, 108, 110, 111, 112, 114, 118, 119, 120, 122, 123, 124, 125, 126, 132, 140, 144, 145
Offset: 1
Examples
24 is 11000 in binary. This binary representation has three 0's and 3 divides 24. So 24 is in the sequence.
Links
- Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Programs
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C
#include
int main(int argc, char *argv[]) { for(int n=1; n< 500; n++) { int digs=0; int nshifted=n; while(nshifted) { digs += 1- nshifted & 1; nshifted >>= 1; } if ( digs) if( n % digs == 0 ) printf("%d, ",n); } } // R. J. Mathar, Apr 03 2006 -
Haskell
a117890 n = a117890_list !! (n-1) a117890_list = [x | x <- [1..], let z = a023416 x, z > 0, mod x z == 0] -- Reinhard Zumkeller, Mar 31 2015
Formula
a(n) <= A117891(n). - R. J. Mathar, Apr 03 2006
a(n) mod A023416(a(n)) = 0. - Reinhard Zumkeller, Nov 22 2007
Extensions
More terms from R. J. Mathar, Apr 03 2006
Comments