A324256 - OEIS

%I #11 Mar 01 2019 03:01:08

%S 37,28201,34687,65587,2089951,4091797,8340613,8161477,10124833,

%T 18927067,37179433,37393633,25855567,64346413,107160373,95150203,

%U 159440893,238973101,257658061,277743397,322210813,256268149,349883707,578403913,814865497,752724457,704710543

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

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

%C Analogous to A002046 as A019279 is analogous to A000396.

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

%t 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

%o (PARI) f(n) = sigma(sigma(n)) - n;

%o lista(nn) = {for (n=1, nn, my(fn = f(n)); if ((fn > n) && (f(fn) == n), print1(fn, ", ")););} \\ _Michel Marcus_, Feb 20 2019

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

%K nonn

%O 1,1

%A _Amiram Eldar_, Feb 19 2019