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A178642 Primes p such that primorial(p)/2 - 2 is not prime. 2
3, 29, 37, 43, 47, 59, 61, 67, 73, 79, 83, 89, 97, 101, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

EXAMPLE

3*5*7*11*13*17*19*23*29 - 2 = 43*167*450473 is composite.

MATHEMATICA

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

Transpose[Select[With[{pros=Rest[FoldList[Times, 1, Prime[Range[100]]]]}, Table[ {Prime[n], pros[[n]]}, {n, 100}]], !PrimeQ[Last[#]/2-2]&]][[1]] (* Harvey P. Dale, Mar 02 2012 *)

CROSSREFS

Cf. A002110, A096177, A096547, A178641.

Sequence in context: A055062 A086174 A338518 * A125854 A167278 A341210

Adjacent sequences:  A178639 A178640 A178641 * A178643 A178644 A178645

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, May 31 2010

STATUS

approved

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Last modified October 22 09:29 EDT 2021. Contains 348160 sequences. (Running on oeis4.)