%I #6 Mar 30 2012 18:35:41
%S 1,2,2,1,2,1,5,1,1,2,1,1,2,1,1,1,2,1,1,3,1,1,1,1,1,2,1,2,1,1,1,1,3,1,
%T 2,1,1,1,1,1,2,1,2,1,4,1,1,1,5,1,1,2,1,1,1,1,5,1,1,2,1,1,1,2,1,1,1,1,
%U 3,1,1,1,1,1,1,1,1,1,1,1,2,1,2,1,1,1,1,1,3,1,1,1,1,1,1,1,1,3,1,1,1,1,1,5,1
%N Least k such that nextprime(k*prime(n)) - k*prime(n) is nonprime.
%C The first time a value of m appears is when n equals 1, 2, 20, 45, 7. I can find no value greater than 5 for n's up through 12,500,000.
%t NextPrim[n_] := Block[{k = n + 1}, While[ !PrimeQ[k], k++ ]; k]; f[n_] := Block[{k = 1}, While[ PrimeQ[ NextPrim[k*Prime[n]] - k*Prime[n]], k++ ]; k]; Table[ f[n], {n, 1, 105}]
%K nonn
%O 1,2
%A _David W. Wilson_ and _Robert G. Wilson v_, May 31 2002