A162884 - OEIS

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A162884

Half the difference between the larger and smaller term of the n-th amicable pair.

32, 13, 152, 272, 68, 56, 1155, 560, 6532, 32, 2025, 9009, 4490, 11835, 8775, 392, 5756, 13210, 2240, 2288, 9032, 2860, 42272, 40652, 55426, 21592, 8944, 8575, 5840, 1755, 34648, 38072, 33536, 38296, 4664, 57796, 35296, 30555, 10856, 41384, 88965, 22496

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..42.

FORMULA

a(n) = A066539(n)/2.

a(n) = (A259180(2n) - A259180(2n-1))/2. - Omar E. Pol, Oct 26 2017

EXAMPLE

a(7)=1155 because the 7th pair of amicable numbers is 12285 and 14595; and (14595-12285)/2=1155.

MAPLE

read("transforms3") ; L002046 := BFILETOLIST("b002046.txt") : L002025 := BFILETOLIST("b002025.txt") : A066539 := proc(n) global L002046, L002025; op(n, L002046)-op(n, L002025) ; end:

A162884 := proc(n) A066539(n)/2 ; end: seq(A162884(n), n=1..100) ; # R. J. Mathar, Jul 19 2009

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 &]]]]/2] (* Michael De Vlieger, Oct 26 2017 *)

CROSSREFS

Cf. A063990, A066539, A259180.

Sequence in context: A305584 A316691 A275470 * A029771 A302684 A302519

Adjacent sequences: A162881 A162882 A162883 * A162885 A162886 A162887

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Jul 16 2009

EXTENSIONS

Terms resorted along with A066539 by R. J. Mathar, Jul 19 2009

STATUS

approved