A128662 Numbers k such that p(k+1)# + p(k)# - p(k-1)# + 1 is prime where p(i)# = product of first i primes = A002110(i).
8, 13, 14, 15, 30, 41, 71, 85, 97, 132, 221, 282, 424, 509, 1346, 1348, 3684, 8224
Offset: 1
Programs
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Mathematica
Flatten[Position[Partition[FoldList[Times,Prime[Range[1350]]],3,1],?(PrimeQ[ #[[2]]+#[[3]]-#[[1]]+1]&),1,Heads->False]]+1 (* _Harvey P. Dale, May 30 2018 *)
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PARI
P(n) = factorback(primes(n)); \\ A002110 isok(k) = ispseudoprime(P(k+1)+P(k)-P(k-1)+1); \\ Michel Marcus, Sep 11 2022
Extensions
a(17) from Michael S. Branicky, Jun 23 2023
a(11) corrected and a(18) from Michael S. Branicky, Dec 11 2024