A394803 a(n) is the least prime number of the form A392155(k) + ... + A392155(n) for some k in 1..n.

2, 3, 3, 7, 5, 11, 7, 31, 17, 53, 11, 23, 13, 103, 29, 31, 17, 19, 37, 173, 41, 43, 23, 47, 73, 179, 53, 29, 109, 139, 31, 149, 389, 67, 251, 71, 37, 569, 401, 79, 41, 83, 43, 953, 89, 673, 47, 797, 97, 1103, 101, 103, 53, 107, 109, 1217, 113, 1303, 59, 1451

Offset

1,1

Comments

All prime numbers appear in this sequence.

Links

Rémy Sigrist, Table of n, a(n) for n = 1..10000

Rémy Sigrist, Colored logarithmic scatterplot of the first 25000 terms (where the color is function of n-k: black pixels when n-k = 0, gray pixels when n-k = 1, other colors otherwise)

Example

For n = 25:
- A392155(25) = 25 is not prime,
- A392155(24) + A392155(25) = 24 + 26 = 50 is not prime,
- A392155(23) + A392155(24) + A392155(25) = 23 + 24 + 26 = 73 is prime,
- so a(25) = 73.

Prog

(PARI) { s = 0; for (n = 1, #a = vector(60), for (v = 1, oo, if (!bittest(s, v), t = v; forstep (k = n, 1, -1, if (isprime(t += a[k]), s += 2^(a[n] = v); print1 (t", "); break (2); ); ); ); ); ); }

Crossrefs

Cf. A392155.

Sequence in context: A141061 A256447 A076557 * A228548 A140407 A063670

Adjacent sequences: A394800 A394801 A394802 * A394804 A394805 A394806

Keyword

nonn

Author

Rémy Sigrist, Apr 02 2026

Status

approved