1,2

Table of n, a(n) for n=1..9.

3*4-1=11 11 and 13 twin primes, 3*6-1=17 17 and 19 twin primes a(1)=1

15*16-1=239 239 and 241 twin primes, 15*18-1=269 269 and 271 twin primes a(2)=2

Cf. A138303.

Sequence in context: A174107 A253927 A281481 * A173939 A328433 A118182

Adjacent sequences: A138298 A138299 A138300 * A138302 A138303 A138304

nonn

Pierre CAMI, Mar 14 2008

approved