A355958 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..55.

EXAMPLE

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.

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 *)

PROG

(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);

CROSSREFS

Cf. A104589, A355967.

Sequence in context: A273731 A013914 A228718 * A222123 A222124 A222125

Adjacent sequences: A355955 A355956 A355957 * A355959 A355960 A355961

KEYWORD

nonn

AUTHOR

Michel Marcus, Jul 21 2022

STATUS

approved