cp's OEIS Frontend

A271499 Positive numbers n such that the number of 1's in the binary expansion of n is not a power of 2.

%I A271499 #17 Apr 16 2016 20:47:41
%S A271499 7,11,13,14,19,21,22,25,26,28,31,35,37,38,41,42,44,47,49,50,52,55,56,
%T A271499 59,61,62,63,67,69,70,73,74,76,79,81,82,84,87,88,91,93,94,95,97,98,
%U A271499 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 A271499 Positive numbers n such that the number of 1's in the binary expansion of n is not a power of 2.
%H A271499 Michel Marcus, <a href="/A271499/b271499.txt">Table of n, a(n) for n = 1..10000</a>
%e A271499 127 = 1111111_2 has seven 1's, so is a term (this distinguishes the sequence from A235336).
%t A271499 Select[Range@ 140, ! IntegerQ@ Log2@ First@ DigitCount[#, 2] &] (* _Michael De Vlieger_, Apr 16 2016 *)
%o A271499 (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 A271499 (Python)
%o A271499 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 A271499 Complement of A143071.
%Y A271499 Similar to but different from A075930, A235336 and A271500.
%K A271499 nonn,base
%O A271499 1,1
%A A271499 _N. J. A. Sloane_, Apr 16 2016