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A145256
a(n) = the smallest integer > n that is non-coprime to n and has the same number of 1's in its binary representation as n has.
5
4, 6, 8, 10, 9, 14, 16, 12, 12, 22, 18, 26, 21, 27, 32, 34, 20, 38, 24, 28, 26, 46, 33, 35, 28, 30, 35, 58, 39, 62, 64, 36, 36, 42, 40, 74, 42, 45, 48, 82, 44, 86, 50, 51, 54, 94, 66, 56, 52, 54, 56, 106, 57, 110, 70, 60, 60, 118, 75, 122, 93, 111, 128, 80, 68, 134, 72, 81, 74
OFFSET
2,1
COMMENTS
a(n) <= 2n since 2n is trivially a multiple of n and multiplying a number by 2 adds a 0 in base 2. - Stefan Steinerberger, Oct 17 2008
LINKS
MATHEMATICA
a[n_] := Block[{}, i = n + 1; While[GCD[i, n] == 1 || Not[DigitCount[n, 2, 1] == DigitCount[i, 2, 1]], i++ ]; i]; Table[a[n], {n, 2, 100}] (* Stefan Steinerberger, Oct 17 2008 *)
PROG
(PARI) a(n) = for (m=n+1, oo, if (gcd(m, n)>1 && hammingweight(m)==hammingweight(n), return (m))) \\ Rémy Sigrist, Feb 06 2020
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Leroy Quet, Oct 05 2008
EXTENSIONS
Edited and corrected by Stefan Steinerberger, Oct 17 2008
STATUS
approved