A255218 - OEIS

A255218

Numbers k such that 12*k+1, 24*k+1, 36*k+1 and 72*k+1 are all prime.

28, 103, 190, 253, 355, 848, 1328, 1783, 1898, 1958, 1988, 2170, 2213, 3003, 3533, 3808, 3913, 3988, 4450, 4488, 4593, 4800, 5460, 5808, 5853, 6448, 6545, 6903, 7103, 7238, 7295, 7400, 7483, 7693, 8533, 9310, 9780, 10260, 10885, 12185, 12628, 15513, 16163

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OFFSET

1,1

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harvey P. Dale)

Umberto Cerruti, Pseudoprimi di Fermat e numeri di Carmichael (in Italian), p. 14.

MATHEMATICA

Select[Range[10000], PrimeQ[12 # + 1] && PrimeQ[24 # + 1] && PrimeQ[36 # + 1] && PrimeQ[72 # + 1] &]

Select[Range[17000], AllTrue[{12, 24, 36, 72}#+1, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, May 16 2016 *)

PROG

(Magma) [n: n in [0..20000] | IsPrime(12*n+1) and IsPrime(24*n+1) and IsPrime(36*n+1) and IsPrime(72*n+1)]; /* or */ [n: n in [0..20000] | forall{i: i in Divisors(6) | IsPrime(12*i*n+1)}];

CROSSREFS

Subsequence of A110801 and A111174.

Cf. A255578.

Sequence in context: A219691 A212777 A130281 * A168254 A219380 A263200

Adjacent sequences: A255215 A255216 A255217 * A255219 A255220 A255221

KEYWORD

nonn

AUTHOR

Vincenzo Librandi, Feb 26 2015

STATUS

approved