A066539 - OEIS

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

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OFFSET

1,1

COMMENTS

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

REFERENCES

For references see A002025.

LINKS

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

FORMULA

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

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

EXAMPLE

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

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 *)

CROSSREFS

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

Sequence in context: A303319 A275469 A178542 * A095390 A033384 A073327

Adjacent sequences: A066536 A066537 A066538 * A066540 A066541 A066542

KEYWORD

nonn

AUTHOR

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

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

STATUS

approved