OFFSET
1,1
EXAMPLE
12*3^2-1=107, 107 and 109 twin primes so k(1)=12
18*107^2-1=206081, 206081 and 206083 twin primes so k(2)=18
CROSSREFS
KEYWORD
hard,nonn
AUTHOR
Pierre CAMI, Oct 01 2005
EXTENSIONS
Removed misleading mention of a(n) in NAME. - R. J. Mathar, Jun 20 2021
STATUS
approved