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A163158 Primes of the form f^2-2, where f is a Fibonacci number. +0
2
2, 7, 23, 167, 439, 3023, 7919, 54287, 974167, 2550407, 32522920134767, 3372041405099481407, 9839618880490124200692486211717007, 724995932728680612729658820311719934835368079 (list; graph; listen)
OFFSET

1,1

COMMENT

A basic heuristic suggests that this sequence is infinite with about k * log_phi(n) members below n.

Indices of associated Fibonacci numbers are 3, 4, 5, 7, 8, 10, 11, 13, 16, 17, 34, 46, 83, 109, 113, 158, 181, 203, 350, 490, 491, 565, 1024, 1114, 2800, 4222, 4847, 4961, 11507, 12554, ...

EXAMPLE

2^2-2=2, 3^2-2=7, 5^2-2=23

MATHEMATICA

f[n_]:=Fibonacci[n]^2-2; lst={}; Do[If[PrimeQ[f[n]], AppendTo[lst, f[n]]], {n, 6!}]; lst

CROSSREFS

Cf. A000045, A028871

Sequence in context: A002494 A032264 A139522 this_sequence A112089 A075062 A022497

Adjacent sequences: A163155 A163156 A163157 this_sequence A163159 A163160 A163161

KEYWORD

nonn,new

AUTHOR

Vladimir Orlovsky (4vladimir(AT)gmail.com), Jul 21 2009

EXTENSIONS

Comments from Charles R Greathouse IV (charles.greathouse(AT)case.edu), Nov 09 2009

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Last modified November 23 17:09 EST 2009. Contains 167438 sequences.


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