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A255218
Numbers k such that 12*k+1, 24*k+1, 36*k+1 and 72*k+1 are all prime.
2
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
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
KEYWORD
nonn
AUTHOR
Vincenzo Librandi, Feb 26 2015
STATUS
approved