|
| |
|
|
A092207
|
|
Numbers n such that n and n+2 are semiprimes.
|
|
8
| |
|
|
4, 33, 49, 55, 85, 91, 93, 119, 121, 141, 143, 159, 183, 185, 201, 203, 213, 215, 217, 219, 235, 247, 265, 287, 289, 299, 301, 303, 319, 321, 327, 339, 391, 393, 411, 413, 415, 445, 451, 469, 471, 515, 517, 527, 533, 535, 543, 551, 579, 581, 589, 633, 667
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,1
|
|
|
LINKS
| Eric Weisstein's World of Mathematics, Semiprime
|
|
|
MATHEMATICA
| PrimeFactorExponentsAdded[n_] := Plus @@ Flatten[Table[ #[[2]], {1}] & /@ FactorInteger[n]]; Select[ Range[ 668], PrimeFactorExponentsAdded[ # ] == PrimeFactorExponentsAdded[ # + 2] == 2 &]
Select[Range[700], PrimeOmega[#]==PrimeOmega[#+2]==2&] (* From Harvey P. Dale, Aug 20 2011 *)
|
|
|
CROSSREFS
| Cf. A056809, A070552, A092125, A092126, A092127, A092128, A092129, A082919, A092209.
Sequence in context: A059904 A145645 A042831 * A133630 A066645 A027169
Adjacent sequences: A092204 A092205 A092206 * A092208 A092209 A092210
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| Robert G. Wilson v (rgwv(AT)rgwv.com) and Zak Seidov (zakseidov(AT)yahoo.com), Feb 24 2004
|
| |
|
|
