A302490 Fewest number of distinct prime factors in any product of a_1*a_2*...*a_t where n = a_1 < a_2 < ... < a_t = A006255(n) and the product is square.

0, 2, 2, 1, 2, 2, 2, 3, 1, 3, 3, 3, 3, 4, 3, 1, 2, 2, 2, 3, 3, 3, 2, 2, 1, 3, 4, 3, 2, 4, 2, 3, 5, 4, 4, 2, 3, 3, 3, 3, 3, 3, 3, 4, 3, 3, 3, 3, 1, 4, 4, 5, 3, 4, 5, 3, 4

Offset

1,2

Comments

a(n^2) = A001221(n).

Links

Table of n, a(n) for n=1..57.

Example

a(14) = 4 because 14 * 15 * 16 * 18 * 20 * 21 has four distinct prime factors (2, 3, 5, and 7) and no other square product of a strictly increasing sequence starting at 14 and ending at 21 has fewer distinct prime factors.

Crossrefs

Cf. A001221, A006255, A280244.

Cf. A066400, A245530.

Sequence in context: A029350 A166597 A375325 * A316841 A000003 A234398

Adjacent sequences: A302487 A302488 A302489 * A302491 A302492 A302493

Keyword

nonn,more

Author

Peter Kagey, Apr 08 2018

Status

approved