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%I #41 Mar 04 2024 01:14:55
%S 220,284,220,284,220,284,220,284,220,284,220,284,220,284,220,284,220,
%T 284,220,284,220,284,220,284,220,284,220,284,220,284,220,284,220,284,
%U 220,284,220,284,220,284,220,284,220,284,220,284,220,284,220,284,220,284
%N Aliquot sequence starting at 220.
%C A period 2 sequence.
%C The sum of the proper divisors of 220 is 284 and the sum of the proper divisors of 284 is 220.
%C Sierpiński's book has typos for n = 1 and 3 (280 instead of 284).
%C Also continued fraction expansion of (7810+sqrt(61000005))/71. - _Bruno Berselli_, Jan 18 2012
%D Wacław Sierpiński, Czym sie zajmuje teoria liczb. Warsaw: PW "Wiedza Powszechna", 1957, p. 138.
%H J. Perrott, <a href="https://doi.org/10.24033/bsmf.394">Sur une proposition empirique énoncée au Bulletin</a>, Bulletin de la S. M. F., tome 17 (1889), pp. 155-156.
%H Wikipedia, <a href="http://en.wikipedia.org/wiki/Aliquot_sequence">Aliquot sequence</a>.
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,1).
%F a(2*n) = 220, a(2*n+1) = 284.
%F a(n+1) = A001065(a(n)). - _R. J. Mathar_, Oct 11 2017
%e a(0) = 220, a(1) = sigma(220) - 220 = 284.
%t RecurrenceTable[{a[n] == DivisorSigma[1, a[n - 1]] - a[n - 1], a[0] == 220}, a, {n, 51}]
%Y Cf. A001065, A063990.
%K nonn,easy
%O 0,1
%A _Arkadiusz Wesolowski_, Jan 05 2012
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