A062894 The prime indices of sequence A067836 (that sequence is conjectured to contain only primes).

1, 2, 3, 4, 6, 5, 7, 8, 9, 12, 21, 10, 11, 14, 22, 16, 23, 19, 13, 15, 41, 35, 42, 27, 20, 17, 45, 39, 29, 33, 28, 54, 26, 37, 46, 61, 47, 59, 40, 31, 57, 18, 24, 58, 36, 43, 49, 64, 80, 106, 67, 60, 65, 63, 48, 94, 85, 51, 73, 122, 105, 100, 113, 138, 104, 115, 75, 32, 82

Offset: 1

Author

Frank Buss (fb(AT)frank-buss.de), Feb 13 2002

Keywords

• nonn

Examples

			a(12)=10 because a(12) in sequence A067836 is 29, which is the 10th prime number.
		

Links

• Robert Price, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A067836.

Programs

Mathematica

Join[{1}, a = 2; f = 1; Table[f = f*a; a = NextPrime[f + 1] - f; k = 1; While[Prime[k] != a, k++]; k, {n, 2, 69}]] (* Jayanta Basu, Aug 10 2013 *)

Python

from sympy import primepi, nextprime
def A062894_gen(): # generator of terms
    a, f = 2, 1
    yield 1
    while True:
        yield primepi(a:=nextprime((f:=f*a)+1)-f)
A062894_list = list(islice(A062894_gen(),30)) # Chai Wah Wu, Sep 09 2023

Extensions

Edited by Dean Hickerson, Jun 10 2002