OFFSET
1,2
PROG
(PARI) a(n) = {if (n == 1, return (1)); k = 1; if (! isprime(n), while (! isprime(k*n+1), k++), while (isprime(k*n+1), k++)); k*n+1; } \\ Michel Marcus, Sep 17 2013
CROSSREFS
KEYWORD
nonn,less
AUTHOR
Amarnath Murthy, Nov 15 2005
EXTENSIONS
a(3) corrected and more terms added by Michel Marcus, Sep 17 2013
STATUS
approved