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A199718
Numbers k such that 6*k-5 is composite, but 6*k-1 is prime.
1
5, 9, 10, 15, 23, 25, 29, 30, 32, 40, 42, 43, 44, 45, 49, 58, 60, 65, 70, 72, 75, 80, 85, 87, 93, 94, 95, 98, 99, 100, 107, 109, 110, 114, 117, 120, 133, 135, 137, 140, 155, 158, 159, 163, 164, 170, 172, 175, 177, 184, 185, 192, 194, 197, 198, 199, 204, 205
OFFSET
1,1
LINKS
MATHEMATICA
Select[Range[2, 205], ! PrimeQ[6 # - 5] && PrimeQ[6 # - 1] &] (* _T. N. Noe_, Nov 09 2011 *)
PROG
(Magma) [ p div 6 +1: n in [4..204] | not IsPrime(p-4) and p mod 6 eq 5 where p is NthPrime(n) ]; // Bruno Berselli, Nov 09 2011
CROSSREFS
Cf. A186243.
Sequence in context: A235033 A327593 A282757 * A155470 A266399 A351205
KEYWORD
nonn,easy
AUTHOR
STATUS
approved