A023273 -id:A023273

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A244086

Primes p such that p remains prime through 7 iterations of function f(x) = 2*x + 3.

+10
0

477727, 507757, 30596497, 33145687, 36180527, 61192997, 141339217, 148590307, 193394347, 297180617, 374066267, 395534747, 398001547, 419795137, 488716897

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..15.

MATHEMATICA

Select[Prime[Range[600000]], And@@PrimeQ[NestList[2 # + 3 &, #, 7]] &]

PROG

(Magma) [p: p in PrimesUpTo(600000000) | forall{i: i in [1..7] | IsPrime(2^i*p+3*(2^i-1))}];

CROSSREFS

Cf. similar sequences with k iterations: A067076 (k=1), A023242 (k=2), A023273 (k=3), A023303 (k=4), A023331 (k=5), A175160 (k=6), this sequence (k=7).

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Jun 24 2014

EXTENSIONS

Inappropriate MAGMA code simplified and other terms added from Bruno Berselli, Jun 24 2014

STATUS

approved

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