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A161719 Least number k such that 7^(2^i) + k is prime for i = 0,1,..,n-1. 0
4, 4, 10, 40, 990, 8712, 1691820, 69466840, 6173190532, 4139897208540 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..10.

EXAMPLE

a(5) = 990 because k = 990 is the minimal k such that N = 7^(2^i) + k is prime for i = 0, 1, 2, 3, 4; N = 997, 1039, 3391, 5765791, 33232930570591. But 7^(2^5) + 990 is divisible by 37 and four other primes.

CROSSREFS

Cf. A129613, A225560 A226281, A226707.

Sequence in context: A145598 A320392 A117881 * A161433 A180498 A107856

Adjacent sequences:  A161716 A161717 A161718 * A161720 A161721 A161722

KEYWORD

nonn,more

AUTHOR

Robin Garcia, Jun 16 2013

EXTENSIONS

a(10) from Giovanni Resta, Jun 16 2013

STATUS

approved

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Last modified September 15 18:22 EDT 2019. Contains 327082 sequences. (Running on oeis4.)