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

1,1

Comments

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

Links

Table of n, a(n) for n=1..57.

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

Crossrefs

Cf. A253106, A001748, A100484.

Sequence in context: A367018 A087247 A307507 * A235690 A271568 A229271

Adjacent sequences: A171153 A171154 A171155 * A171157 A171158 A171159

Keyword

nonn,easy,less

Author

Juri-Stepan Gerasimov, Dec 04 2009

Extensions

Edited by Charles R Greathouse IV, Mar 25 2010

Status

approved