A330571 Square of number of unordered factorizations of n as n = i*j.

1, 1, 1, 4, 1, 4, 1, 4, 4, 4, 1, 9, 1, 4, 4, 9, 1, 9, 1, 9, 4, 4, 1, 16, 4, 4, 4, 9, 1, 16, 1, 9, 4, 4, 4, 25, 1, 4, 4, 16, 1, 16, 1, 9, 9, 4, 1, 25, 4, 9, 4, 9, 1, 16, 4, 16, 4, 4, 1, 36, 1, 4, 9, 16, 4, 16, 1, 9, 4, 16, 1, 36, 1, 4, 9, 9, 4, 16, 1, 25, 9, 4, 1, 36, 4, 4, 4, 16, 1, 36, 4, 9, 4, 4, 4, 36

Offset: 1

Author

N. J. A. Sloane, Jan 08 2020

Keywords

• nonn

Comments

Unordered analog of A035116.

For background references see A330570.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Equals A038548(n)^2.

Cf. A035116.

Programs

Mathematica

a[n_] := Ceiling[DivisorSigma[0, n] / 2]^2; Array[a, 100] (* Amiram Eldar, Apr 19 2024 *)

PARI

a(n) = (numdiv(n) \/ 2)^2; \\ Amiram Eldar, Apr 19 2024