OFFSET
1,1
EXAMPLE
27*2*3*5/2=405; 401 and 409 are consecutive primes with a gap of 8, for n=3, k=27
MATHEMATICA
nn=60; Module[{prmrls=(Rest[FoldList[Times, 1, Prime[Range[nn]]]])/2, k, c}, Table[ k=1; c=k*prmrls[[n]]; While[NextPrime[c]-c!=4||c-NextPrime[c, -1]!=4, k++; c= k*prmrls[[n]]]; k, {n, nn}]] (* Harvey P. Dale, Mar 26 2013 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Aug 28 2004
STATUS
approved