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A128032 Numbers k such that (19^k - 3^k)/16 is prime. 28
73, 271, 421, 2711 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are primes.

No other terms <= 10^5. - Robert Price, Aug 27 2011

LINKS

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

MATHEMATICA

k=16; Select[ Prime[ Range[1, 200] ], PrimeQ[ ((k+3)^# - 3^#)/k ]& ]

PROG

(PARI) is(n)=isprime((19^n-3^n)/16) \\ Charles R Greathouse IV, Feb 17 2017

CROSSREFS

Cf. A028491, A057468, A059801, A121877, A128024, A128025, A128026, A128027, A128028, A128029, A128030, A128031.

Sequence in context: A071392 A305473 A142434 * A142489 A033244 A140857

Adjacent sequences:  A128029 A128030 A128031 * A128033 A128034 A128035

KEYWORD

hard,more,nonn

AUTHOR

Alexander Adamchuk, Feb 11 2007

EXTENSIONS

2711 from Farideh Firoozbakht, Apr 07 2007

STATUS

approved

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Last modified June 24 21:16 EDT 2019. Contains 324337 sequences. (Running on oeis4.)