1,2

a(6) > 500 if it exists. - Felix FrÃ¶hlich, Sep 15 2019

Table of n, a(n) for n=1..5.

1*2/2 +1 = 2 prime so a(1)=1 as 2=prime(1).

1*2*3/(2*3) +1 = 2 prime so a(2)=2 as 3=prime(2).

1*2*3*4*5/(2*3*5) +1 = 5 prime so a(3)=3 as 5=prime(3).

(PARI) isok(k) = isprime(prime(k)!/prod(i=1, k, prime(i)) + 1); \\ Michel Marcus, Sep 15 2019

Cf. A092435 (p!/p#), A124082.

Sequence in context: A154253 A097961 A145556 * A112098 A144545 A085326

Adjacent sequences: A124080 A124081 A124082 * A124084 A124085 A124086

nonn,more

Pierre CAMI, Nov 25 2006

approved