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A291634 Number of primitive sequences n = b_1 < b_2 < ... < b_t = A006255(n) such that b_1*b_2*...*b_t is a perfect square. 0
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 8, 1, 11, 1, 1, 2, 20, 1, 1, 2, 1, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,11

COMMENTS

A primitive sequence is one such that no proper, nonempty subsequence has a product that is a perfect square.

Trivially, a(n) <= A259527(n). If A259527(n) = 1, then a(n) = 1.

LINKS

Table of n, a(n) for n=1..28.

MAPLE

For n = 22 the a(22) = 2 solutions are:

22 * 24 * 33 = 132^2, and

22 * 27 * 32 * 33 = 792^2.

Note that 22 * 24 * 25 * 33 = 660^2 is not a solution because the subsequence [25] has a square product.

CROSSREFS

Cf. A006255, A259527.

Sequence in context: A274613 A066975 A355879 * A098877 A225212 A091088

Adjacent sequences: A291631 A291632 A291633 * A291635 A291636 A291637

KEYWORD

nonn,more

AUTHOR

Peter Kagey, Aug 29 2017

STATUS

approved

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Last modified December 7 17:25 EST 2022. Contains 358668 sequences. (Running on oeis4.)