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A128161 a(n) = numbers n such that 2^n modulo Fibonacci(n) is prime, i.e., A057862(n) is prime. 2
5, 7, 9, 13, 14, 19, 25, 88, 100, 113, 130, 440, 503, 2800, 3203, 3346, 4357, 6496, 8822, 16316, 20039, 22381, 30481, 33779, 71864, 110390, 127796, 441190, 457249 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Corresponding primes in A057862 are {2,11,2,37,173,1663,18257,447876604131364627,55437674149894825801,...}.

LINKS

Table of n, a(n) for n=1..29.

MAPLE

select(n->isprime(2 &^n mod combinat:-fibonacci(n)), [$1..3000]); # Muniru A Asiru, Jul 17 2018

MATHEMATICA

Do[f=PowerMod[2, n, Fibonacci[n]]; If[PrimeQ[f], Print[{n, f}]], {n, 1, 503}]

PROG

(PARI) is(n)=ispseudoprime(2^n%fibonacci(n)) \\ Charles R Greathouse IV, Jun 19 2017

(PFGW)

ABC2 2^$a % F($a)

a: from 5 to 1000000

// Charles R Greathouse IV, Jun 19 2017

CROSSREFS

Cf. A057862 = 2^n modulo Fibonacci(n). Cf. A128162, A128163.

Sequence in context: A115913 A200268 A251627 * A141106 A047478 A048974

Adjacent sequences:  A128158 A128159 A128160 * A128162 A128163 A128164

KEYWORD

hard,more,nonn

AUTHOR

Alexander Adamchuk, Feb 19 2007

EXTENSIONS

a(14)-a(19) from Stefan Steinerberger, Jun 10 2007

More terms from Ryan Propper, Jan 11 2008

a(25)-a(26) from Donovan Johnson, Sep 03 2008

a(27) from Charles R Greathouse IV, Jun 20 2017

a(28)-a(29) from Charles R Greathouse IV, Jun 30 2017

STATUS

approved

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Last modified January 15 20:47 EST 2019. Contains 319184 sequences. (Running on oeis4.)