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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..105.

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

Cf. A001358, A014499.

Sequence in context: A281945 A163107 A275840 * A057748 A057747 A281965

Adjacent sequences:  A178062 A178063 A178064 * A178066 A178067 A178068

KEYWORD

nonn,base,easy

AUTHOR

Juri-Stepan Gerasimov, May 18 2010

EXTENSIONS

a(56) corrected by R. J. Mathar, May 23 2010

STATUS

approved

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Last modified July 17 02:10 EDT 2019. Contains 325092 sequences. (Running on oeis4.)