login
A086096
Semiprimes with a semiprime number of 1's in their binary representation.
2
15, 39, 46, 51, 57, 58, 77, 85, 86, 95, 106, 111, 119, 123, 141, 142, 159, 166, 169, 177, 178, 183, 187, 201, 202, 209, 215, 219, 221, 226, 235, 237, 249, 267, 278, 287, 291, 298, 303, 305, 323, 326, 329, 335, 365, 371, 377, 393, 394, 407, 411, 413, 417, 427
OFFSET
1,1
LINKS
EXAMPLE
The sixth semiprime = 15 = '1111' with four 1's, so 15 is a term.
MATHEMATICA
binWt[n_] := DigitCount[n, 2, 1]; seqQ[n_] := PrimeOmega[n] == 2 && PrimeOmega[binWt[n]] == 2; Select[Range[500], seqQ] (* Amiram Eldar, Dec 14 2019 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jason Earls, Jul 09 2003
STATUS
approved