A178641 Primes p such that primorial(p)/2 + 2 is composite.

11, 17, 19, 23, 41, 43, 53, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 311, 313, 317, 331, 337

Offset

1,1

Links

Table of n, a(n) for n=1..55.

Example

3*5*7*11 + 2 = 13*89 is composite.

Mathematica

pp=1; lst={}; Do[p=Prime[n]; pp*=p; If[ !PrimeQ[pp+2], AppendTo[lst, p]], {n, 2, 2*5!}]; lst

Crossrefs

Cf. A002110, A096177, A178642, A178648.

Sequence in context: A049593 A216664 A019412 * A226682 A111257 A032677

Adjacent sequences: A178638 A178639 A178640 * A178642 A178643 A178644

Keyword

nonn

Author

Vladimir Joseph Stephan Orlovsky, May 31 2010

Status

approved