1,1

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.

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

Cf. A094753.

Cf. A005574.

Sequence in context: A278263 A236188 A242593 * A214061 A260300 A182291

Adjacent sequences: A094749 A094750 A094751 * A094753 A094754 A094755

nonn

Amarnath Murthy, May 29 2004

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

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

approved