A085448 Primes having a semiprime number of 1's in their binary representation.

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

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