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

Author

Jason Earls, Aug 14 2003

Keywords

• easy
• nonn
• base

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?

Examples

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

Links

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

Crossrefs

Cf. A001358, A081092.

Programs

Mathematica

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