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Positive numbers n such that the number of 1's in the binary expansion of n is not a power of 2.
2

%I #17 Apr 16 2016 20:47:41

%S 7,11,13,14,19,21,22,25,26,28,31,35,37,38,41,42,44,47,49,50,52,55,56,

%T 59,61,62,63,67,69,70,73,74,76,79,81,82,84,87,88,91,93,94,95,97,98,

%U 100,103,104,107,109,110,111,112,115,117,118,119,121,122,123,124,125,126,127,131,133,134,137,138,140

%N Positive numbers n such that the number of 1's in the binary expansion of n is not a power of 2.

%H Michel Marcus, <a href="/A271499/b271499.txt">Table of n, a(n) for n = 1..10000</a>

%e 127 = 1111111_2 has seven 1's, so is a term (this distinguishes the sequence from A235336).

%t Select[Range@ 140, ! IntegerQ@ Log2@ First@ DigitCount[#, 2] &] (* _Michael De Vlieger_, Apr 16 2016 *)

%o (PARI) lista(nn) = {for (n=1, nn, my(nbd = hammingweight(n)); if (!((nbd==1) || (nbd==2) || (ispower(nbd,,&k) && (k==2))), print1(n, ", ")););} \\ _Michel Marcus_, Apr 16 2016

%o (Python)

%o A271499_list = [n for n in range(1,10**6) if bin(bin(n).count('1')).count('1') != 1] # _Chai Wah Wu_, Apr 16 2016

%Y Complement of A143071.

%Y Similar to but different from A075930, A235336 and A271500.

%K nonn,base

%O 1,1

%A _N. J. A. Sloane_, Apr 16 2016