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A280516 Amicable pairs where only deficient aliquot parts are considered. 1
1184, 1210, 6232, 6368, 10744, 10856, 66928, 66992, 522405, 525915, 643336, 652664, 5459176, 5495264, 7677248, 7684672, 16137628, 16150628, 25596544, 25640096, 26090325, 26138475, 28118032, 28128368, 34364912, 34380688, 133178325, 133471275, 164733752, 166212808 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Subsequence of A063990.

LINKS

Table of n, a(n) for n=1..30.

EXAMPLE

Deficient aliquot parts of 1184 are 1,2,4,8,16,32,37,74,148,296,592 and their sum is 1210.

Deficient aliquot parts of 1210 are 1,2,5,10,11,22,55,110,121,242,605 and their sum is 1184.

MAPLE

with(numtheory): P:=proc(q) local a, b, c, d, k, n; for n from 1 to q do

a:=sort([op(divisors(n))]); b:=0; for k from 1 to nops(a)-1 do if 2*a[k]>sigma(a[k]) then b:=b+a[k]; fi; od;

c:=sort([op(divisors(b))]); d:=0; for k from 1 to nops(c)-1 do if 2*c[k]>igma(c[k]) then d:=d+c[k]; fi; od; if d=n and d<>b then print(n); fi; od; end: P(10^6);

MATHEMATICA

defQ[n_] := DivisorSigma[1, n] < 2n; s[n_] := DivisorSum[n, #&, #<n && defQ[#]&]; seq={}; Do[m=s[n]; If[m>n && s[m]==n, AppendTo[seq, {n, m}]], {n, 1, 10^5}]; Flatten[seq] (* Amiram Eldar, Jan 26 2019 *)

CROSSREFS

Cf. A063990, A259180, A280515.

Sequence in context: A320716 A269017 A328064 * A205994 A345540 A345792

Adjacent sequences:  A280513 A280514 A280515 * A280517 A280518 A280519

KEYWORD

nonn,tabf

AUTHOR

Paolo P. Lava, Jan 04 2017

EXTENSIONS

More terms from Amiram Eldar, Jan 26 2019

STATUS

approved

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Last modified November 29 14:50 EST 2021. Contains 349416 sequences. (Running on oeis4.)