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A244113 Primes p such that f(p), f(f(p)), f(f(f(p))), and  f(f(f(f(p)))) are all prime, where f(x) = x^2+3x+1. 0
3, 1628779, 2481113, 3260683, 3520229, 9733123, 10671253, 10673129, 11772809, 36758303, 45459353, 45594019, 58552279, 64597903, 66539353, 74674559, 83471243, 96765313, 115623929, 117479039, 131701183, 133500553, 145010533, 163341319, 163845719, 166410353, 167197243, 169948223 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..28.

EXAMPLE

p = 3, f(p) = 19,  f(19) = 419, f(419) = 176819 , and  f(176819) = 31265489219 all prime.

MATHEMATICA

Select[Prime[Range[10^7]], AllTrue[Rest[NestList[#^2+3#+1&, #, 4]], PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Apr 12 2018 *)

CROSSREFS

Subsequence of A250027. Cf. A094210, A153590.

Sequence in context: A309225 A137131 A229725 * A324425 A117721 A229092

Adjacent sequences:  A244110 A244111 A244112 * A244114 A244115 A244116

KEYWORD

nonn

AUTHOR

Zak Seidov, Nov 11 2014

STATUS

approved

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Last modified November 12 07:03 EST 2019. Contains 329052 sequences. (Running on oeis4.)