1,1

1. a(6)>2*10^9 2. (C. Pomerance) The prime k-tuple conjecture implies the sequence is infinite.

93801=3*19*23*71, and 2*93801+1, 2+3*19*23*71, 3+2*19*23*71, 19+2*3*23*71, 71+2*3*19*23, 2*3+19*23*71, 2*19+3*23*71, 2*23+3*19*23*71, 2*71+3*19*23, 3*19+2*23*71, 3*23+2*19*71, 3*71+2*19*23, 19*23+2*3*71, 19*71+2*3*23, 23*71+2*3*19 are all primes and 93801 is smallest such integer, so a(1)=93801

Cf. A128276.

Sequence in context: A140932 A025042 A023945 this_sequence A126708 A029754 A110845

Adjacent sequences: A128274 A128275 A128276 this_sequence A128278 A128279 A128280

hard,more,nonn

Kok Seng Chua (chuakokseng(AT)hotmail.com), Feb 23 2007