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A275996 Numbers n whose abundance is 64: sigma(n) - 2n = 64. 3
108, 220, 6808, 8968, 14008, 24448, 66928, 552568, 786208, 1020568, 5303488, 8229568, 10001848, 133685248, 499722448, 2608895488, 4733164768, 7163795488, 13707973408, 14468025568, 16122444736 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Any term x = a(m) of this sequence can be used with any term y of A275997 to satisfy the property (sigma(x)+sigma(y))/(x+y) = 2, which is a necessary (but not sufficient) condition for two numbers to be amicable.

The smallest amicable pair is (220, 284) = (a(2), A275997(2)) = (A063990(1), A063990(2)), where 284 - 220 = 64 is the abundance of 220 and the deficiency of 284.

The amicable pair (66928, 66992) = (a(7), A275997(11)) = (A063990(18), A063990(19)), and 66992 - 66928 = 64 is the abundance of 66928 and the deficiency of 66992.

LINKS

Table of n, a(n) for n=1..21.

EXAMPLE

a(1) = 108, since sigma(108) - 2*108 = 280 - 216 = 64.

PROG

(PARI) isok(n) = sigma(n) - 2*n == 64; \\ Michel Marcus, Dec 30 2016

CROSSREFS

Subsequence of A005101.

Cf. A002025, A063990, A275997, A088831, A088832, A088833, A141547, A175989, A275701, A066539, A259180.

Sequence in context: A044340 A044721 A095050 * A235292 A202202 A202195

Adjacent sequences:  A275993 A275994 A275995 * A275997 A275998 A275999

KEYWORD

nonn

AUTHOR

Timothy L. Tiffin, Aug 16 2016

EXTENSIONS

a(14)-a(15) from Michel Marcus, Dec 30 2016

a(16)-a(21) from Lars Blomberg, Jan 12 2017

STATUS

approved

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Last modified October 22 19:53 EDT 2019. Contains 328319 sequences. (Running on oeis4.)