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A104243 Semiprimes of the form prime(n) + prime(n+2) - prime(n+1). 2
4, 9, 15, 21, 25, 35, 39, 49, 55, 65, 69, 77, 85, 91, 93, 111, 123, 133, 141, 155, 161, 169, 183, 209, 215, 235, 247, 249, 265, 291, 309, 323, 327, 339, 341, 355, 361, 365, 377, 391, 393, 411, 437, 445, 451, 453, 505, 511, 515, 529, 551, 553, 565, 581, 583, 611 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..10000

MATHEMATICA

Union[Select[First[#]+Last[#]-#[[2]]&/@Partition[Prime[Range[200]], 3, 1], PrimeOmega[ #]==2&]] (* Harvey P. Dale, Sep 11 2013 *)

PROG

(PARI) lista(nn) = {sps = Set(); for (n=1, nn, if (bigomega(sp=prime(n) + prime(n+2) - prime(n+1))==2, sps = Set(concat(sps, sp))); ); print(sps); } \\ Michel Marcus, Jun 03 2013

CROSSREFS

Sequence in context: A313279 A107986 A062721 * A313280 A313281 A313282

Adjacent sequences:  A104240 A104241 A104242 * A104244 A104245 A104246

KEYWORD

nonn

AUTHOR

Giovanni Teofilatto, Apr 03 2005

EXTENSIONS

Corrected and extended by Rick L. Shepherd, May 18 2005

STATUS

approved

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Last modified October 22 10:24 EDT 2019. Contains 328317 sequences. (Running on oeis4.)