OFFSET
1,1
EXAMPLE
1*2*3*5*7/2 - 2 = 103, 1*2*3*5*7/2 + 2 = 107, 103 and 107 are both primes, so for n=4, k=1.
MATHEMATICA
Primorial[n_] := Product[Prime[i], {i, 1, n}]; f[n_] := Block[{p = Primorial[n]/2, k = 1}, While[ !PrimeQ[k*p - 2] || !PrimeQ[k*p + 2], k++ ]; k]; Table[ f[n], {n, 50}] (* Robert G. Wilson v, Aug 19 2004 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Aug 18 2004
EXTENSIONS
More terms from Robert G. Wilson v, Aug 19 2004
STATUS
approved