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A128073 Numbers n such that (3^n + 16^n)/19 is prime. 10
5, 17, 61, 673, 919, 2089, 86939 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All terms are primes.

a(8) > 10^5 - Robert Price, Jun 29 2013

LINKS

Table of n, a(n) for n=1..7.

MATHEMATICA

k=16; Do[ p=Prime[n]; f=(3^p+k^p)/(k+3); If[ PrimeQ[f], Print[p]], {n, 1, 100} ]

PROG

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

CROSSREFS

Cf. A007658 = numbers n such that (3^n + 1)/4 is prime. Cf. A057469 = numbers n such that (3^n + 2^n)/5 is prime. Cf. A122853 = numbers n such that (3^n + 5^n)/8 is prime. Cf. A128066, A128067, A128068, A128069, A128070, A128071, A128072, A128074, A128075. Cf. A059801 = numbers n such that 4^n - 3^n is prime. Cf. A121877 = numbers n such that (5^n - 3^n)/2 is a prime. Cf. A128024, A128025, A128026, A128027, A128028, A128029, A128030, A128031, A128032.

Sequence in context: A273836 A273704 A146444 * A051736 A301560 A099528

Adjacent sequences:  A128070 A128071 A128072 * A128074 A128075 A128076

KEYWORD

hard,more,nonn

AUTHOR

Alexander Adamchuk, Feb 14 2007

EXTENSIONS

a(5) from Alexander Adamchuk, Feb 14 2007

a(6) and a(7) from Robert Price, Jun 29 2013

STATUS

approved

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Last modified June 19 17:16 EDT 2019. Contains 324222 sequences. (Running on oeis4.)