A222265 -id:A222265

Search: a222265 -id:a222265

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page 1

A225191

Numbers n such that (15^n + 2^n)/17 is prime.

+10
3

3, 67, 199, 479, 563, 2243, 2579, 6599, 7951, 10099, 10909, 13759

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

All terms are odd primes.

a(13) > 10^5.

LINKS

Table of n, a(n) for n=1..12.

MATHEMATICA

Select[Prime[Range[1, 100000]], PrimeQ[(15^# + 2^#)/17]&]

PROG

(PARI) forprime(p=3, 10^6, if(ispseudoprime((15^p + 2^p)/17), print1(p, ", ") ) ); \\ Joerg Arndt, Jul 29 2013

CROSSREFS

Cf. A057181, A125956, A125957, A222265.

KEYWORD

nonn,hard,more

AUTHOR

Robert Price, May 07 2013

EXTENSIONS

Removed incorrect first term of "2".

STATUS

approved

A224507

Numbers n such that (17^n + 2^n)/19 is prime.

+10
2

5, 7, 113, 193, 211, 701, 797, 907, 4153

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

All terms are prime.

a(10) > 10^5.

LINKS

Table of n, a(n) for n=1..9.

MATHEMATICA

Select[Prime[Range[1, 100000]], PrimeQ[(17^# + 2^#)/19]&]

PROG

(PARI) is(n)=ispseudoprime((17^n+2^n)/19) \\ Charles R Greathouse IV, Jun 06 2017