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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.
3
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
1,1
LINKS
EXAMPLE
532 = 1000010100 in base 2 and 532 = 2^2*7*19 hence 532 is in the sequence.
MATHEMATICA
Select[Range[2, 640, 2], DigitCount[#, 2, 1] == PrimeNu[#] &] (* Amiram Eldar, Jan 11 2020 *)
PROG
(PARI) for(n=1, 80000, if(sum(i=1, length(binary(n)), component(binary(n), i))==(-1)^n*omega(n), print1(n, ", ")))
CROSSREFS
Sequence in context: A177917 A071594 A306263 * A090778 A097380 A114270
KEYWORD
base,easy,nonn
AUTHOR
Benoit Cloitre, Jun 01 2002
STATUS
approved