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A224691 Numbers n such that (13^n - 4^n)/9 is prime. 1
2, 5, 19, 109, 157, 8521, 26017, 26177 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are prime.

a(9) > 10^5.

LINKS

Table of n, a(n) for n=1..8.

MATHEMATICA

Select[Prime[Range[1, 100000]], PrimeQ[(13^# - 4^#)/9]&]

PROG

(PARI) is(n)=ispseudoprime((13^n-4^n)/9) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A004063, A028491, A057468, A059801, A121877, A128024, A128025, A128026, A128027, A128028, A128029, A128030, A128031, A128032, A210506, A128347.

Sequence in context: A211207 A107882 A328977 * A192445 A089126 A113346

Adjacent sequences:  A224688 A224689 A224690 * A224692 A224693 A224694

KEYWORD

nonn,hard,more

AUTHOR

Robert Price, Apr 15 2013

STATUS

approved

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Last modified November 27 04:21 EST 2020. Contains 338677 sequences. (Running on oeis4.)