A045614 Maximal elements of pairs of "Super Unitary Amicable Numbers", sorted by their minimal elements.

35, 155, 142, 224, 272, 601, 1033, 956, 1847, 2512, 3004, 2407, 2224, 3055, 3357, 4288, 5637, 4511, 7536, 5824, 6460, 7756, 8637, 7619, 8721, 7965, 14044, 14974, 16992, 13503, 14656, 14508, 14108, 18261, 22576, 17542, 16251, 20638, 18108, 29960, 27328, 24736

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..40410 (terms below 10^10, terms 1..1000 from Donovan Johnson)

Eric Weisstein's World of Mathematics, Super Unitary Amicable Pair

Formula

usigma(usigma(a)) = usigma(usigma(b)) = a+b where a<b and usigma(n) = A034448(n) is the sum of the unitary divisors of n. This sequence gives the values of b; A045613 gives the values of a.

Mathematica

usigma[n_] := If[n == 1, 1, Times @@ (1 + Power @@@ FactorInteger[n])]; u[n_] := usigma[usigma[n]] - n; s = {}; Do[m = u[n]; If[m > n && u[m] == n, AppendTo[s, m]], {n, 1, 10000}]; s (* Amiram Eldar, Feb 18 2019 *)

Crossrefs

Cf. A045613, A034448.

Sequence in context: A048629 A133534 A005339 * A154074 A260867 A015219

Adjacent sequences: A045611 A045612 A045613 * A045615 A045616 A045617

Keyword

nonn

Author

Yasutoshi Kohmoto

Extensions

Edited by Dean Hickerson, Nov 06 2006

Offset corrected by Donovan Johnson, Jul 26 2012

More terms from Amiram Eldar, Feb 18 2019

Status

approved