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A160031 Primes p such that p^4 + 2*3^4 is prime. 2
5, 13, 19, 43, 71, 83, 97, 101, 107, 109, 127, 149, 179, 193, 197, 211, 233, 241, 311, 353, 383, 401, 421, 541, 577, 599, 607, 619, 641, 647, 683, 709, 727, 751, 769, 827, 877, 883, 941, 967, 991, 1009, 1061, 1097, 1109, 1187, 1289, 1373, 1381, 1409, 1439 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For primes p, q, r the sum p^4 + q^4 + r^4 can be prime only if at least one of p, q, r equals 3. This sequence is the special case q = r = 3.

It is conjectured that the sequence is infinite.

There are prime twins (107, 109) and other consecutive primes (193, 197) in the sequence.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..1000

EXAMPLE

p = 5: 5^4 + 2*3^4 = 787 is prime, so 5 is in the sequence.

p = 7: 7^4 + 2*3^4 = 2563 = 11*233, so 7 is not in the sequence.

p = 107: 107^4 + 2*3^4 = 131079763 is prime, so 107 is in the sequence.

p = 109: 109^4 + 2*3^4 = 141158323 is prime, so 109 is in the sequence.

MATHEMATICA

Select[Prime[Range[300]], PrimeQ[#^4+162]&] (* Harvey P. Dale, May 10 2018 *)

PROG

(MAGMA) [ p: p in PrimesUpTo(1450) | IsPrime(p^4+162) ]; // Klaus Brockhaus, May 03 2009

(PARI) is(n)=isprime(n) && isprime(n^4+162) \\ Charles R Greathouse IV, Jun 07 2016

CROSSREFS

Cf. A158979, A159829, A160022.

Sequence in context: A290515 A082093 A045455 * A154634 A232655 A175866

Adjacent sequences:  A160028 A160029 A160030 * A160032 A160033 A160034

KEYWORD

easy,nonn

AUTHOR

Ulrich Krug (leuchtfeuer37(AT)gmx.de), Apr 30 2009

EXTENSIONS

Edited and extended beyond 683 by Klaus Brockhaus, May 03 2009

STATUS

approved

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Last modified September 15 12:22 EDT 2019. Contains 327078 sequences. (Running on oeis4.)