A061072 Smallest integer with A002191(n) divisors, i.e., the number of divisors equals the sum of the divisors of a different number.

1, 4, 6, 12, 64, 24, 60, 4096, 192, 144, 180, 240, 360, 960, 720, 1073741824, 840, 1260, 786432, 36864, 1680, 2880, 15360, 2520, 6300, 6720, 2359296, 5040, 3221225472, 14400, 983040, 10080, 206158430208, 184320, 15120, 20160, 25200, 2985984, 9663676416, 27720

Offset: 1

Author

Labos Elemer, May 28 2001

Keywords

• nonn

Examples

			For all values of sigma(x), i.e., of A002191, the smallest number with identical number of divisors is found at A005179(sigma(x)). E.g., 8 = A002191(6) is a possible divisor sum. The smallest number which has 8 divisors is 24 = A005179(8). See also comment to A008864, with special solutions of equation: sigma(x) = tau(y) = A000203(x) = A000005(y).
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..959

Crossrefs

Cf. A000005, A000203, A002191, A005179, A008864.

Formula

A000005(a(n)) = A002191(n). I.e., if function A000005 is applied to this sequence, then values of A002191 are obtained. These terms are taken from A005179.

a(n) = A005179(A002191(n)). - David Wasserman, Jun 06 2002

Extensions

More terms from David Wasserman, Jun 06 2002

Offset corrected by Sean A. Irvine, Jan 19 2023