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A197038 Numbers n such that (2^n + 3^n)/97 is prime. 1
12, 412, 436, 916 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..4.

EXAMPLE

a(1) = 12 => (2^12+3^12)/97 = 5521 is prime ;

(2^a(2)+3^a(2))/97 has 195 digits ;

(2^a(3)+3^a(3))/97 has 207 digits ;

(2^a(4)+3^a(4))/97 has 436 digits ;

MATHEMATICA

lst={}; Do[If[PrimeQ[(2^k+3^k)/97], AppendTo[lst, k]], {k, 1000}]; lst

Select[Range[10000], PrimeQ[(2^#+3^#)/97]&] (* Harvey P. Dale, Aug 22 2013 *)

PROG

(PARI) is(n)=ispseudoprime((2^n+3^n)/97) \\ Charles R Greathouse IV, Jun 13 2017

CROSSREFS

Cf. A181628, A181636.

Sequence in context: A003772 A211078 A299382 * A282883 A163971 A249065

Adjacent sequences:  A197035 A197036 A197037 * A197039 A197040 A197041

KEYWORD

nonn,hard

AUTHOR

Michel Lagneau, Oct 08 2011

STATUS

approved

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Last modified February 19 13:23 EST 2020. Contains 332044 sequences. (Running on oeis4.)