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A264778 Numbers n such that 6*n+1, 3*n+2, 6*n+7 are all odd semiprimes. 3
113, 157, 193, 209, 211, 223, 231, 235, 251, 259, 307, 319, 345, 401, 415, 437, 463, 489, 521, 563, 567, 581, 599, 663, 673, 677, 701, 719, 731, 733, 771, 789, 811, 855, 857, 875, 883, 923, 935, 951, 961, 983, 993, 995, 997, 1017, 1023, 1031, 1047, 1089, 1097 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Or odd numbers n such that the arithmetic progression 6*n+1, 6*n+4, 6*n+7 consists of twice a semiprime sandwiched between two semiprimes.

LINKS

Table of n, a(n) for n=1..51.

MATHEMATICA

fQ[n_] := And[OddQ@ n, PrimeOmega@ n == 2]; Select[Range@ 1100,

AllTrue[{6 # + 1, 3 # + 2, 6 # + 7}, fQ] &] (* Michael De Vlieger, Nov 24 2015, Version 10 *)

PROG

(PARI) for(n=1, 1e4, if(n%2==1 && bigomega(6*n+1)==2 && bigomega(3*n+2)==2 && bigomega(6*n+7)==2, print1(n, ", "))); \\ Altug Alkan, Nov 24 2015

CROSSREFS

Cf. A001358, A263510, A264779.

Sequence in context: A136078 A230255 A167631 * A142303 A152929 A142180

Adjacent sequences:  A264775 A264776 A264777 * A264779 A264780 A264781

KEYWORD

nonn

AUTHOR

Vladimir Shevelev and Peter J. C. Moses, Nov 24 2015

STATUS

approved

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Last modified May 26 19:44 EDT 2019. Contains 323597 sequences. (Running on oeis4.)