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A178065
Number of 1's in binary representation of n-th semiprime.
2
1, 2, 2, 2, 3, 4, 3, 3, 3, 3, 2, 2, 3, 3, 4, 4, 3, 4, 5, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 5, 5, 5, 6, 4, 6, 5, 5, 6, 5, 5, 6, 2, 3, 3, 4, 4, 5, 3, 3, 5, 5, 6, 3, 4, 4, 4, 4, 6, 5, 6, 3, 4, 4, 5, 5, 5, 4, 5, 5, 6, 5, 5, 6, 6, 4, 6, 6, 7, 6, 7, 7, 3, 3, 3, 4, 3, 4, 6, 3, 4, 5, 4, 5, 5, 5, 6, 4, 5, 5, 7, 3, 4, 4, 5
OFFSET
1,2
EXAMPLE
a(1)=1 because the first semiprime is 4 = 100_2.
a(2)=2 because the second semiprime is 6 = 110_2.
PROG
(PARI) lista(nn) = {for (n=2, nn, if (bigomega(n)==2, print1(norml2(binary(n)), ", ")); ); } \\ Michel Marcus, Jun 05 2013
CROSSREFS
Sequence in context: A281945 A163107 A275840 * A366636 A366655 A057748
KEYWORD
nonn,base,easy
AUTHOR
EXTENSIONS
a(56) corrected by R. J. Mathar, May 23 2010
STATUS
approved