A066539 Difference between larger and smaller terms of n-th amicable pair.

64, 26, 304, 544, 136, 112, 2310, 1120, 13064, 64, 4050, 18018, 8980, 23670, 17550, 784, 11512, 26420, 4480, 4576, 18064, 5720, 84544, 81304, 110852, 43184, 17888, 17150, 11680, 3510, 69296, 76144, 67072, 76592, 9328, 115592, 70592, 61110, 21712

Offset: 1

Author

Robert A. Stump (bee_ess107(AT)yahoo.com), Jan 06 2002

Keywords

• nonn

Comments

Values are sorted along increasing A002025. - R. J. Mathar, Jul 19 2009, Jul 23 2009

Examples

			a(7) = 2310 because the 7th pair of amicable numbers is 12285 and 14595; and 14595 - 12285 = 2310.
		

References

• For references see A002025.

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..415523

Crossrefs

Cf. A002025, A002046, A063990, A259180 (amicable pairs).

Programs

Mathematica

With[{s = PositionIndex@Array[DivisorSigma[1, #] &, 10^6]}, Flatten@ Map[Differences, Apply[Join, Map[Function[n, Select[Subsets[Lookup[s, n], {2}], Total@ # == n &]], Sort@ Select[Keys@ s, Length@ Lookup[s, #] > 1 &]]]]] (* Michael De Vlieger, Oct 22 2017 *)

Formula

a(n) = A002046(n) - A002025(n).

a(n) = A259180(2n) - A259180(2n-1). - Omar E. Pol, Oct 22 2017

Extensions

Sorted on smaller term for alignment with A002046 and A002025. - R. J. Mathar, Jul 19 2009

A-number in comment corrected by R. J. Mathar, Jul 23 2009