A362267 For n >= 0, a(n) is the least integer i >= 0 such that n + p_1 + ... + p_i = q, q prime number, or a(n) = -1 if no such i exists. Here p_1 is the least prime >= n, p_1 < p_2 < ... < p_i are prime numbers (A000040).

1, 1, 0, 0, 15, 0, 1, 0, 1, 12, 13, 0, 3, 0, 1, 4, 29, 1, 1, 0, 1, 2, 25, 0, 1, 4, 7, 8, 13, 0, 1, 0, 7, 6, 1, 2, 1, 0, 1, 4, 21, 0, 7, 0, 5, 10, 19, 0, 1, 6, 1, 2, 85, 0, 1, 4, 17, 6, 5, 0, 11, 0, 15, 4, 1, 20, 3, 0, 1, 14, 3, 0, 3, 0, 5, 22, 17, 2, 1, 0, 1, 6, 11, 0

Offset

0,5

Links

Table of n, a(n) for n=0..83.

Formula

a(p) = 0 for p prime number.

Example

n = 4: p_1 >= 4 is 5, a(4) = 4 + p_1 + ... + p_i = 4 + 5 + 7 + 11 + 13 + 17 + 19 + 23 + 29 + 31 + 37 + 41 + 43 + 47 + 53 + 59 = 439 which is a prime number, thus a(4) = 15.

Crossrefs

Cf. A000040, A007504, A161463.

Sequence in context: A324675 A106239 A271763 * A271339 A202857 A055965

Adjacent sequences: A362264 A362265 A362266 * A362268 A362269 A362270

Keyword

sign

Author

Ctibor O. Zizka, Jul 05 2023

Status

approved