A071596 Even numbers k such that the number of 1's in binary representation of k equals omega(k), the number of distinct primes in the factorization of k.
2, 4, 6, 8, 10, 12, 16, 18, 20, 24, 32, 34, 36, 40, 42, 48, 64, 68, 70, 72, 80, 84, 96, 128, 136, 138, 140, 144, 160, 168, 192, 210, 256, 266, 272, 276, 280, 288, 290, 320, 322, 330, 336, 384, 390, 420, 512, 514, 518, 522, 530, 532, 544, 552, 560, 576, 580, 640
Offset: 1
Examples
532 = 1000010100 in base 2 and 532 = 2^2*7*19 hence 532 is in the sequence.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Programs
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Mathematica
Select[Range[2, 640, 2], DigitCount[#, 2, 1] == PrimeNu[#] &] (* Amiram Eldar, Jan 11 2020 *)
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PARI
for(n=1,80000,if(sum(i=1,length(binary(n)), component(binary(n),i))==(-1)^n*omega(n),print1(n,",")))