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A094752 Largest k such that 2n/k + 1 as well as 2nk+1 are prime, or 0 if no such number exists. 1
2, 4, 6, 2, 10, 6, 14, 16, 9, 20, 1, 24, 26, 7, 5, 8, 0, 36, 0, 40, 21, 2, 1, 24, 5, 13, 54, 56, 1, 30, 0, 4, 66, 0, 7, 36, 74, 0, 1, 20, 1, 84, 0, 4, 90, 0, 94, 8, 0, 1, 1, 0, 1, 27, 110, 28, 0, 116, 0, 120, 0, 124, 126, 0, 130, 66, 134, 1, 1, 5, 0, 72, 146, 37, 150, 0, 0, 156, 0, 160, 9 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

For n=7 the largest k is 14 since 2*7/14+1=2 is prime and 2*7*14+1=197 which is also prime.

LINKS

Table of n, a(n) for n=1..81.

CROSSREFS

Cf. A094753.

Cf. A005574.

Sequence in context: A278263 A236188 A242593 * A214061 A260300 A182291

Adjacent sequences:  A094749 A094750 A094751 * A094753 A094754 A094755

KEYWORD

nonn

AUTHOR

Amarnath Murthy, May 29 2004

EXTENSIONS

Corrected by R. Piyo (nagoya314(AT)yahoo.com), Dec 10 2004

More terms from Franklin T. Adams-Watters, Nov 20 2006

STATUS

approved

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Last modified September 25 18:20 EDT 2017. Contains 292499 sequences.