A355958 Positions where primes occur in A104589.

2, 3, 4, 8, 12, 18, 19, 35, 39, 47, 53, 65, 75, 81, 84, 102, 109, 127, 131, 261, 265, 273, 283, 305, 323, 329, 350, 450, 456, 462, 492, 522, 562, 660, 664, 784, 904, 922, 1081, 1213, 1258, 1406, 1443, 1467, 1549, 1655, 1772, 1774, 1786, 1810, 1901, 1919, 2024, 2144, 2161

Offset: 1

Author

Michel Marcus, Jul 21 2022

Keywords

• nonn

Examples

			The 1st prime in A104589 is 2, and its position is 2, so a(1) = 2.
The 2nd prime in A104589 is 5, and its position is 3, so a(2) = 3.
The 3rd prime in A104589 is 13, and its position is 4, so a(3) = 4.
		

Crossrefs

Cf. A104589, A355967.

Programs

Mathematica

s[1] = 1; s[n_] := s[n] = s[n - 1] + Sum[If[CompositeQ[s[k]], 0, s[k]], {k, 1, n - 1}]; Select[Range[2000], PrimeQ[s[#]] &] (* Amiram Eldar, Jul 21 2022 *)

PARI

lista(nn) = my(last=1, s = 1, list = List()); for (n=2, nn, last += s; if (isprime(last), s += last; listput(list, n));); Vec(list);