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A125216 Semiprimes s such that s-/+4 are primes. 2
9, 15, 33, 57, 93, 177, 237, 267, 393, 453, 573, 597, 687, 723, 933, 1167, 1227, 1293, 1527, 1563, 1623, 1983, 2157, 2217, 2463, 2913, 3327, 3453, 3543, 4353, 4647, 5007, 5277, 5403, 5847, 5853, 6033, 6117, 6207, 6267, 6333, 6393, 7023, 7233, 8013, 8097 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..46.

MATHEMATICA

Reap[Do[p=Prime[i]; If[PrimeQ[p+8]&&Total[Last/@FactorInteger[p+4]]==2, Sow[p+4]], {i, 2*10^3}]][[2, 1]]

Select[Range[8100], PrimeOmega[#]==2&&AllTrue[#+{4, -4}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Oct 29 2017 *)

CROSSREFS

Sequence in context: A155775 A228096 A111148 * A058505 A133763 A146475

Adjacent sequences:  A125213 A125214 A125215 * A125217 A125218 A125219

KEYWORD

nonn

AUTHOR

Zak Seidov, Nov 24 2006

STATUS

approved

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Last modified October 17 13:07 EDT 2021. Contains 348048 sequences. (Running on oeis4.)