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A316712 Numbers k such that 421*2^k+1 is prime. 0
4, 8, 12, 16, 24, 36, 72, 196, 576, 928, 3336, 5172, 5996, 6196, 13204, 28484, 36984, 43740, 58744, 62244, 112876, 127852, 143208, 170612, 174372, 221372, 350356, 832528, 1070460, 1729092 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..30.

Ray Ballinger, Proth Search Page

Ray Ballinger and Wilfrid Keller, List of primes k.2^n + 1 for 300 < k < 600

Y. Gallot, Proth.exe: Windows Program for Finding Large Primes

Wilfrid Keller, List of primes k.2^n - 1 for k < 300

Eric Weisstein's World of Mathematics, Proth Prime

Index entries for sequences of n such that k*2^n-1 (or k*2^n+1) is prime

MAPLE

select(k->isprime(421*2^k+1), [$1..1000]); # Muniru A Asiru, Jan 05 2019

MATHEMATICA

Select[Range[1000], PrimeQ[421*2^# + 1] &]

CROSSREFS

Sequence in context: A291834 A291928 A045783 * A261650 A178731 A071072

Adjacent sequences:  A316709 A316710 A316711 * A316713 A316714 A316715

KEYWORD

nonn,more,hard

AUTHOR

Robert Price, Jan 04 2019

STATUS

approved

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Last modified November 20 05:07 EST 2019. Contains 329323 sequences. (Running on oeis4.)