A390584 Numbers k such that the sum of k consecutive nonprimes equals k^2.

1, 8, 51, 3525, 5280, 7494, 338503, 1053987, 1077148, 2482511, 2850517, 8311987, 241872681

Offset

1,2

Links

Table of n, a(n) for n=1..13.

Example

a(2) = 8: 1 + 4 + 6 + 8 + 9 + 10 + 12 + 14 = 8^2.
a(3) = 51: The sum of the 51 consecutive composite numbers 18, 20, 21, 22, ..., 80, 81, 82, 84 equals 2601 = 51^2.

Crossrefs

Cf. A018252, A389751, A390585.

Sequence in context: A226199 A267637 A238648 * A341626 A215834 A180319

Adjacent sequences: A390581 A390582 A390583 * A390585 A390586 A390587

Keyword

nonn,hard,more

Author

Hugo Pfoertner, Nov 11 2025

Extensions

a(7)-a(9) from Michael S. Branicky, Nov 11 2025

a(10)-a(13) from Bert Dobbelaere, Nov 12 2025

Status

approved