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A243310 Smallest k such that both prime(k)*prime(k+1) +/- 2^n are prime, or 0 if no such k exists. 0
1, 2, 2, 2, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n) = 0 for n > 5?

a(n) = 0 for 5 < n <= 10000. Heuristics suggest that there are no other nonzero terms. - Charles R Greathouse IV, Jun 04 2014

LINKS

Table of n, a(n) for n=0..86.

EXAMPLE

a(0) = 1 because prime(1)*prime(1+1)-2^0 = 5 and prime(1)*prime(1+1) + 2^0 = 7 are prime,

a(1) = 2 because prime(2)*prime(2+1)-2^1 = 13 and prime(2)*prime(2+1)+2^1 = 17 are prime,

a(2) = 2 because prime(2)*prime(2+1)-2^2 = 11 and prime(2)*prime(2+1)+2^2 = 19 are prime,

a(3) = 2 because prime(2)*prime(2+1)-2^3 = 7 and prime(2)*prime(2+1)+2^3 = 23 are prime.

CROSSREFS

Cf. A006094.

Sequence in context: A230291 A059288 A217670 * A197727 A176884 A071443

Adjacent sequences:  A243307 A243308 A243309 * A243311 A243312 A243313

KEYWORD

nonn,less

AUTHOR

Juri-Stepan Gerasimov, Jun 03 2014

STATUS

approved

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Last modified February 24 18:24 EST 2018. Contains 299628 sequences. (Running on oeis4.)