The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A321084 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A321084

Primes prime(n) such that 1 + Sum_{k=1..n} 2^(prime(k)-1) is prime.
(history; published version)

#25 by Bruno Berselli at Tue Nov 27 03:54:49 EST 2018

STATUS

reviewed

approved

#24 by Michel Marcus at Tue Nov 27 03:17:02 EST 2018

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proposed

reviewed

#23 by Michael De Vlieger at Wed Oct 31 22:31:09 EDT 2018

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editing

proposed

#22 by Michael De Vlieger at Wed Oct 31 22:30:59 EDT 2018

MATHEMATICA

Prime@ Select[Range[10^3], PrimeQ[1 + Total@ Array[2^(Prime[#] - 1) &, #]] &] (* Michael De Vlieger, Oct 31 2018 *)

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proposed

editing

#21 by Thomas Ordowski at Tue Oct 30 11:55:06 EDT 2018

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editing

proposed

#20 by Thomas Ordowski at Tue Oct 30 11:54:43 EDT 2018

CROSSREFS

Cf. A000040, A000043, A080355, A113878.

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proposed

editing

#19 by Thomas Ordowski at Tue Oct 30 03:37:05 EDT 2018

STATUS

editing

proposed

#18 by Thomas Ordowski at Tue Oct 30 03:35:36 EDT 2018

NAME

Primes p prime(n) such that 1 + 2^(2-1) + 2^(3-1) + 2^(5-1) + 2^(7-1) + 2^(11-Sum_{k=1) + ... + n} 2^(pprime(k)-1) is prime.

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proposed

editing

#17 by Thomas Ordowski at Tue Oct 30 03:27:51 EDT 2018

STATUS

editing

proposed

#16 by Thomas Ordowski at Tue Oct 30 03:26:35 EDT 2018

COMMENTS

Let S(n) = Sum_{k=1..n} 2^(prime(k)-1). Conjecture: q(n) = 1 + S(n) is prime if and only if 2^S(n) == 1 (mod q(n)).

STATUS

proposed

editing