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%I #10 Oct 27 2017 10:15:47
%S 32,13,152,272,68,56,1155,560,6532,32,2025,9009,4490,11835,8775,392,
%T 5756,13210,2240,2288,9032,2860,42272,40652,55426,21592,8944,8575,
%U 5840,1755,34648,38072,33536,38296,4664,57796,35296,30555,10856,41384,88965,22496
%N Half the difference between the larger and smaller term of the n-th amicable pair.
%F a(n) = A066539(n)/2.
%F a(n) = (A259180(2n) - A259180(2n-1))/2. - _Omar E. Pol_, Oct 26 2017
%e a(7)=1155 because the 7th pair of amicable numbers is 12285 and 14595; and (14595-12285)/2=1155.
%p read("transforms3") ; L002046 := BFILETOLIST("b002046.txt") : L002025 := BFILETOLIST("b002025.txt") : A066539 := proc(n) global L002046,L002025; op(n,L002046)-op(n,L002025) ; end:
%p A162884 := proc(n) A066539(n)/2 ; end: seq(A162884(n),n=1..100) ; # _R. J. Mathar_, Jul 19 2009
%t 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 *)
%Y Cf. A063990, A066539, A259180.
%K nonn
%O 1,1
%A _Juri-Stepan Gerasimov_, Jul 16 2009
%E Terms resorted along with A066539 by _R. J. Mathar_, Jul 19 2009
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