A097568 Least k such that k*P(n)#/2 - 4 and k*P(n)#/2 + 4 are consecutive primes with a gap of 8, where P(n)=n-th prime, P(n)#=n-th primorial.

93, 31, 27, 15, 9, 85, 5, 19, 47, 107, 35, 9, 109, 7, 55, 595, 63, 61, 133, 5, 21, 79, 109, 163, 561, 233, 99, 311, 165, 295, 731, 27, 459, 471, 705, 1057, 1459, 433, 11, 735, 413, 899, 163, 1085, 581, 13, 23, 945, 69, 3595, 743, 131, 945, 241, 223, 231, 509, 965

Offset

1,1

Links

Table of n, a(n) for n=1..58.

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

Sequence in context: A191948 A278860 A283897 * A086001 A106658 A033413

Adjacent sequences: A097565 A097566 A097567 * A097569 A097570 A097571

Keyword

nonn

Author

Pierre CAMI, Aug 28 2004

Status

approved