A120359 Even refactorable numbers n such that the number r of odd divisors is odd, the number s of even divisors is even, both r and s are divisors of n and n is the first number for which the triple (r,s,t) occurs, where t is the number of divisors of n.

36, 3600, 8100, 10000, 26244, 32400, 142884, 202500, 396900, 518400, 656100, 810000, 1587600, 1679616, 2286144, 2624400, 3572100, 6350400, 9144576, 9922500, 20575296

Offset

1,1

Comments

Note that s is necessarily a multiple of r.

Links

Table of n, a(n) for n=1..21.

Example

a(1)=36 since r=3, s=6 and r+s=9.

Crossrefs

Cf. A033950, A049439. A057265.

Sequence in context: A364175 A209267 A120349 * A194611 A165984 A297021

Adjacent sequences: A120356 A120357 A120358 * A120360 A120361 A120362

Keyword

nonn

Author

Walter Kehowski, Jun 25 2006

Status

approved