The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A357496 Greater of a pair of amicable numbers k < m such that s(k) = m and s(m) = k, where s(k) = A162296(k) - k is the sum of aliquot divisors of k that have a square factor. 3

%I #12 Oct 03 2022 04:11:09

%S 1136,11696,22256,25472,43424,73664,131355,304336,267968,492608,

%T 612704,674920,640305,788697,691292,705344,723392,813728,809776,

%U 1117395,1258335,1559696,1518570,1598368,1821376,2218250,2058944,2678752,2744288,2765024,2848864,2610656,3134224

%N Greater of a pair of amicable numbers k < m such that s(k) = m and s(m) = k, where s(k) = A162296(k) - k is the sum of aliquot divisors of k that have a square factor.

%C Analogous to amicable numbers (A002025 and A002046) with nonsquarefree divisors.

%C The terms are ordered according to their lesser counterparts (A357495).

%C Both members of each pair are necessarily nonsquarefree numbers.

%H Amiram Eldar, <a href="/A357496/b357496.txt">Table of n, a(n) for n = 1..1000</a>

%e 1136 is a term since s(1136) = 880 and s(880) = 1136.

%t s[n_] := Module[{f = FactorInteger[n], p, e}, p = f[[;; , 1]]; e = f[[;; , 2]]; Times @@ ((p^(e + 1) - 1)/(p - 1)) - Times @@ (p + 1) - n]; seq = {}; Do[m = s[n]; If[m > n && s[m] == n, AppendTo[seq, m]], {n, 2, 3*10^6}]; seq

%Y Cf. A162296, A325314, A322609, A357493, A357494, A357495.

%Y Subsequence of A013929.

%Y Similar sequences: A002046, A002953, A126166, A126170, A259039, A292981, A322542, A324709, A348344.

%K nonn

%O 1,1

%A _Amiram Eldar_, Oct 01 2022

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 17 12:36 EDT 2024. Contains 373445 sequences. (Running on oeis4.)