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A085448 Primes having a semiprime number of 1's in their binary representation. 3
23, 29, 43, 53, 71, 83, 89, 101, 113, 139, 149, 163, 197, 263, 269, 277, 281, 293, 311, 317, 337, 347, 349, 353, 359, 373, 389, 401, 449, 461, 467, 523, 547, 571, 593, 599, 619, 643, 673, 683, 691, 739, 773, 797, 811, 821, 839, 853, 857, 881, 907, 937, 977 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Sequence of least prime with the number of 1's in its binary representation equal to n-th semiprime is: 23,311,991,2039,73727,63487,4128767,... What is the prime corresponding to 22?

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

EXAMPLE

The prime 43 = '101011' has four 1's and so is a term.

MATHEMATICA

seqQ[n_] := PrimeQ[n] && PrimeOmega[DigitCount[n, 2, 1]] == 2; Select[Range[1000], seqQ] (* Amiram Eldar, Dec 14 2019 *)

CROSSREFS

Cf. A001358, A081092.

Sequence in context: A227756 A007637 A161723 * A095077 A106989 A106988

Adjacent sequences:  A085445 A085446 A085447 * A085449 A085450 A085451

KEYWORD

easy,nonn,base

AUTHOR

Jason Earls, Aug 14 2003

STATUS

approved

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Last modified July 25 00:32 EDT 2021. Contains 346273 sequences. (Running on oeis4.)