

A002504


Numbers x such that 1 + 3x*(x1) is a ("cuban") prime (cf. A002407).
(Formerly M0522 N0188)


6



2, 3, 4, 5, 7, 10, 11, 12, 14, 15, 18, 24, 25, 26, 28, 29, 31, 33, 35, 38, 39, 42, 43, 46, 49, 50, 53, 56, 59, 63, 64, 67, 68, 75, 81, 82, 87, 89, 91, 92, 94, 96, 106, 109, 120, 124, 126, 129, 130, 137, 141, 143, 148, 154, 157, 158, 159, 165, 166, 171, 172
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OFFSET

1,1


REFERENCES

A. J. C. Cunningham, On quasiMersennian numbers, Mess. Math., 41 (1912), 119146.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).


LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000


EXAMPLE

a(1) = 2 since A002407(1) = 7 = 1 + 3k*(k1) with k=2 is the smallest prime of that form.


MATHEMATICA

Select[Range[500], PrimeQ[1 + 3 # (#  1)] &] (* T. D. Noe, Jan 30 2013 *)


PROG

(PARI) for(k=1, 999, isprime(3*k*(k1)+1)&print1(k", ")) \\ M. F. Hasler, Nov 28 2007


CROSSREFS

Cf. A002407, A133431.
Sequence in context: A047502 A117092 A285276 * A133431 A305705 A123091
Adjacent sequences: A002501 A002502 A002503 * A002505 A002506 A002507


KEYWORD

nonn


AUTHOR

N. J. A. Sloane


EXTENSIONS

Edited, updated (1 is no longer regarded as a prime) and extended by M. F. Hasler, Nov 28 2007


STATUS

approved



