A280516 Amicable pairs where only deficient aliquot parts are considered.

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

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