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A049494 a(n) and a(n)+4^k are primes at least for k=1,2,3,4. 3
7, 37, 163, 757, 967, 1303, 2293, 2377, 8677, 8803, 9157, 9277, 14827, 15667, 16417, 20113, 27763, 29863, 41953, 53593, 56527, 56893, 61027, 67153, 69763, 74827, 79333, 83203, 90007, 95467, 111577, 129277, 135193, 137383, 142543, 151783 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

EXAMPLE

7,7+4=11,7+16=23,7+64=71,7+256=263 are all primes: it is the smallest such quintet.

MATHEMATICA

Select[Prime[Range[15000]], AllTrue[#+{4, 16, 64, 256}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Jan 22 2018 *)

PROG

(PARI) isok(n) = isprime(n) && isprime(n+4) && isprime(n+4^2) && isprime(n+4^3) && isprime(n+4^4); \\ Michel Marcus, Dec 31 2013

CROSSREFS

Cf. A023200, A049492, A049493, A049495-A049500.

Sequence in context: A269258 A247308 A175284 * A049495 A169789 A169726

Adjacent sequences:  A049491 A049492 A049493 * A049495 A049496 A049497

KEYWORD

nonn

AUTHOR

Labos Elemer

STATUS

approved

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Last modified August 12 21:10 EDT 2020. Contains 336440 sequences. (Running on oeis4.)