A324256 Larger of super amicable pair m < n defined by sigma(sigma(m)) = sigma(sigma(n)) = m + n.

37, 28201, 34687, 65587, 2089951, 4091797, 8340613, 8161477, 10124833, 18927067, 37179433, 37393633, 25855567, 64346413, 107160373, 95150203, 159440893, 238973101, 257658061, 277743397, 322210813, 256268149, 349883707, 578403913, 814865497, 752724457, 704710543

Offset: 1

Author

Amiram Eldar, Feb 19 2019

Keywords

• nonn

Comments

The terms are ordered according to the their lesser counterparts (A324255).

Analogous to A002046 as A019279 is analogous to A000396.

Examples

			(23, 37) are the first pair since sigma(sigma(23)) = sigma(sigma(37)) = 60 = 23 + 37.
		

Crossrefs

Cf. A000203, A000396, A002046, A019279, A045614 (unitary analog), A051027, A324255.

Programs

Mathematica

seq={}; s[n_]:=DivisorSigma[1,DivisorSigma[1,n]]-n; Do[m=s[n];If[m>n && s[m]==n, AppendTo[seq, m]], {n,1,60000}]; seq

PARI

f(n) = sigma(sigma(n)) - n;
lista(nn) = {for (n=1, nn, my(fn = f(n)); if ((fn > n) && (f(fn) == n), print1(fn, ", ")););} \\ Michel Marcus, Feb 20 2019