

A074259


Gaps between primes p such that 2p+1 is also prime, i.e., SophieGermain primes A005384.


2



1, 2, 6, 12, 6, 12, 12, 30, 6, 24, 18, 42, 6, 12, 42, 6, 12, 30, 12, 66, 60, 12, 12, 48, 18, 84, 48, 12, 6, 24, 36, 24, 18, 48, 102, 42, 60, 6, 12, 18, 54, 120, 6, 60, 120, 30, 12, 30, 18, 12, 48
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OFFSET

1,2


COMMENTS

The first two consecutive identical gaps are 12, 12 between A005384(6..8) = (29, 41, 53).
The first three, four and five identical gaps in a row are equal to 30, 150 and 420, respectively, and occur after A005384(85) = 3299, A005384(29952) = 4866623, and A005384(32361449747) = 22081407211439. These were found by N. Fernandez and G. Resta, see link to discussion on the SeqFan mailing list.  M. F. Hasler, Sep 18 2016


LINKS



MATHEMATICA

Select[Prime[Range[500]], PrimeQ[2#+1]&]//Differences (* Harvey P. Dale, Jul 15 2019 *)


PROG

(PARI) c=0; forprime(p=1+L=2, 10^6, if(isprime(2*p+1), write("primegap.txt", c++, " "pL); L=p)) \\ Edited by M. F. Hasler, Sep 16 2016


CROSSREFS



KEYWORD

nonn


AUTHOR



EXTENSIONS

Edited (name, offset, more terms) by M. F. Hasler, Sep 16 2016


STATUS

approved



