A128659 Numbers n such that p(n+1)#-p(n)#-p(n-1)#-1 is prime where p(i)#=product of first i primes=A002110(i).

3, 4, 5, 6, 7, 9, 13, 14, 20, 30, 40, 44, 86, 101, 135, 152, 171, 205, 4404

Offset

1,1

Links

Table of n, a(n) for n=1..19.

Mathematica

Flatten[Position[Partition[Rest[FoldList[Times, 1, Prime[Range[210]]]], 3, 1], _?(PrimeQ[#[[3]]-#[[2]]-#[[1]]-1]&), {1}, Heads->False]]+1 (* This generates the first 18 terms of the sequence.  To generate the 19th term, change the Range constant to 4410, but it will take a very long time to run. *) (* Harvey P. Dale, Apr 23 2014 *)

Crossrefs

Cf. A002110, A128420, A128421, A128657, A128658, A128660, A128661, A128662.

Sequence in context: A100586 A139372 A226116 * A364083 A022555 A047308

Adjacent sequences: A128656 A128657 A128658 * A128660 A128661 A128662

Keyword

nonn,more

Author

Pierre CAMI, Mar 19 2007

Status

approved