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A172977
Numbers n such that 2*prime(n)-1 and 6*prime(n)-1 are prime.
0
1, 2, 4, 8, 37, 46, 50, 75, 85, 106, 145, 151, 163, 168, 169, 207, 226, 232, 260, 322, 371, 439, 449, 451, 467, 522, 525, 549, 573, 595, 604, 656, 667, 793, 832, 836, 866, 895, 923, 930, 969, 1029, 1125, 1127, 1135, 1148, 1187, 1222, 1544, 1575, 1611, 1614, 1625
OFFSET
1,2
MATHEMATICA
pnQ[n_]:=Module[{pn=Prime[n]}, And@@PrimeQ[{2pn-1, 6pn-1}]]; Select[ Range[ 2000], pnQ] (* Harvey P. Dale, Jan 14 2012 *)
CROSSREFS
Sequence in context: A070897 A180154 A320025 * A018380 A058236 A259120
KEYWORD
nonn,easy,less
AUTHOR
EXTENSIONS
Corrected and extended by Charles R Greathouse IV, Mar 25 2010
STATUS
approved