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A175648
Semiprimes m such that m+4 is also semiprime.
10
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
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
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Corrected (309 removed) by R. J. Mathar, Aug 03 2010
Definition corrected by Zak Seidov, Feb 12 2015
STATUS
approved