A175648 Semiprimes m such that m+4 is also semiprime.

6, 10, 21, 22, 34, 35, 51, 58, 65, 82, 87, 91, 111, 115, 118, 119, 129, 141, 142, 155, 183, 201, 202, 205, 209, 213, 214, 215, 217, 249, 274, 287, 291, 295, 298, 299, 301, 305, 319, 323, 335, 358, 361, 377, 382, 391, 394, 403, 407, 411, 413, 447, 454, 469, 478

Offset

1,1

Links

Zak Seidov, Table of n, a(n) for n = 1..10000

Maple

select(t -> numtheory:-bigomega(t)=2 and numtheory:-bigomega(t+4)=2, [$1..1000]); # Robert Israel, Feb 12 2015

Mathematica

Select[Range@ 480, And[PrimeOmega@ # == 2, PrimeOmega[# + 4] == 2] &] (* Michael De Vlieger, Dec 09 2015 *)

Prog

(PARI) isok(n) = (bigomega(n) == 2) && (bigomega(n+4) == 2); \\ Michel Marcus, Feb 12 2015

Crossrefs

Cf. A001358, A001359, A175612.

Sequence in context: A348838 A254028 A085274 * A178661 A190273 A030007

Adjacent sequences: A175645 A175646 A175647 * A175649 A175650 A175651

Keyword

nonn,easy

Author

Juri-Stepan Gerasimov, Aug 02 2010

Extensions

Corrected (309 removed) by R. J. Mathar, Aug 03 2010

Definition corrected by Zak Seidov, Feb 12 2015

Status

approved