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A199718 Numbers n such that 6*n-5 is composite, but 6*n-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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

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 A164709

Adjacent sequences:  A199715 A199716 A199717 * A199719 A199720 A199721

KEYWORD

nonn,easy

AUTHOR

Eleonora Echeverri-Toro, Nov 09 2011

STATUS

approved

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Last modified August 3 10:39 EDT 2021. Contains 346435 sequences. (Running on oeis4.)