%I #7 Mar 28 2015 22:34:12
%S 4,2,1,1,2,5,2,7,8,5,13,36,3,55,8,5,186,22,17,45,69,16,57,1,34,99,367,
%T 15,39,321,459,17,17,51,215,608,108,431,439,346,405,789,413,268,1744,
%U 70,889,33,42,1883,2489,76,3246,1219,849,214,870,208,197,619,323,3418,39
%N Least k such that k*P(n)#-P(n+2) and k*P(n)#+P(n+2) are both primes with P(i)=i-th prime and P(i)#=i-th primorial.
%e 2*3 - 7 = -1.
%e 2*2*3 - 7 = 5, prime; 2*2*3 + 7 = 19, prime; so for n=2 k=2.
%t Primorial[n_] := Product[ Prime[i], {i, n}]; f[n_] := Block[{k = 1, p = Primorial[n], q = Prime[n + 2]}, While[k*p - q < 2 || !PrimeQ[k*p - q] || !PrimeQ[k*p + q], k++ ]; k]; Table[ f[n], {n, 63}] (* _Robert G. Wilson v_, Aug 31 2004 *)
%K easy,nonn
%O 1,1
%A _Pierre CAMI_, Aug 27 2004
%E More terms from _Robert G. Wilson v_, Aug 31 2004