A364824 Index of prime(n) in A067836, or -1 if prime(n) does not occur in it.

1, 2, 3, 4, 6, 5, 7, 8, 9, 12, 13, 10, 19, 14, 20, 16, 26, 42, 18, 25, 11, 15, 17, 43, 118, 33, 24, 31, 29, 212, 40, 68, 30, 98, 22, 45, 34, 109, 28, 39, 21, 23, 46, 143, 27, 35, 37, 55, 47, 123, 58, 90, 132, 32, 139, 91, 41, 44, 38, 52, 36, 77, 54, 48, 53, 83, 51

Offset: 1

Author

Bert Dobbelaere, Aug 09 2023

Keywords

• nonn

Comments

All terms in A067836 are distinct, making this sequence defined.

If the conjecture holds that A067836 contains only primes, then a(A062894(n)) = n.

If all primes eventually occur in A067836, then all terms in this sequence are positive and A062894(a(n)) = n.

Crossrefs

Cf. A062894, A067836.

Programs

Python

from itertools import count
from sympy import prime, nextprime
def A364824(n):
    a, f, p = 2, 1, prime(n)
    for i in count(1):
        if a == p:
            return i
        a=nextprime((f:=f*a)+1)-f # Chai Wah Wu, Sep 09 2023