A171156 Numbers of the form 2p or 3p where p is a prime greater than 3.

10, 14, 15, 21, 22, 26, 33, 34, 38, 39, 46, 51, 57, 58, 62, 69, 74, 82, 86, 87, 93, 94, 106, 111, 118, 122, 123, 129, 134, 141, 142, 146, 158, 159, 166, 177, 178, 183, 194, 201, 202, 206, 213, 214, 218, 219, 226, 237, 249, 254, 262, 267, 274, 278, 291, 298, 302

Offset: 1

Author

Juri-Stepan Gerasimov, Dec 04 2009

Keywords

• nonn
• easy
• less

Comments

Squarefree semiprimes (A006881) which have exactly one prime factor <=3 [R. J. Mathar, Dec 09 2009]

Crossrefs

Cf. A253106, A001748, A100484.

Programs

Maple

isA171156 := proc(n) local f; f := numtheory[factorset](n) ; if numtheory[bigomega](n) = 2 and nops(f) = 2 then if f = {2,3} then false; else (n mod 2) = 0 or (n mod 3) = 0 ; fi; else false; fi; end:
for n from 10 to 500 do if isA171156(n) then printf("%d,",n) ; fi; od: # R. J. Mathar, Dec 09 2009

Extensions

Edited by Charles R Greathouse IV, Mar 25 2010