A339664 Number of nonempty subsets of divisors of n whose geometric mean is an integer.

1, 2, 2, 5, 2, 4, 2, 8, 5, 4, 2, 10, 2, 4, 4, 15, 2, 10, 2, 10, 4, 4, 2, 16, 5, 4, 8, 10, 2, 8, 2, 26, 4, 4, 4, 63, 2, 4, 4, 16, 2, 8, 2, 10, 10, 4, 2, 30, 5, 10, 4, 10, 2, 16, 4, 16, 4, 4, 2, 20, 2, 4, 10, 45, 4, 8, 2, 10, 4, 8, 2, 196, 2, 4, 10, 10, 4, 8, 2, 30

Offset

1,2

Links

Table of n, a(n) for n=1..80.

Eric Weisstein's World of Mathematics, Geometric Mean

Index entries for sequences related to divisors of numbers

Example

a(12) = 10 subsets: {1}, {2}, {3}, {4}, {6}, {12}, {1, 4}, {3, 12}, {1, 2, 4} and {3, 6, 12}.

Crossrefs

Cf. A027750, A100587, A326027, A339663, A339665, A339666.

Sequence in context: A340839 A257090 A360910 * A124316 A328705 A351346

Adjacent sequences: A339661 A339662 A339663 * A339665 A339666 A339667

Keyword

nonn

Author

Ilya Gutkovskiy, Dec 11 2020

Status

approved