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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 March 26 06:47 EDT 2023. Contains 361529 sequences. (Running on oeis4.)