A324708 - OEIS

%I #9 Dec 29 2021 05:58:09

%S 114,594,1140,5940,8640,10744,12285,13500,44772,60858,62100,67095,

%T 67158,79296,79650,79750,118500,142310,143808,177750,185368,298188,

%U 308220,356408,377784,462330,545238,600392,608580,609928,624184,635624,643336,643776,669900

%N Lesser of tri-unitary amicable numbers pair: numbers (m, n) such that tsigma(m) = tsigma(n) = m + n, where tsigma(n) is the sum of the tri-unitary divisors of n (A324706).

%C The larger counterparts are in A324709.

%H Amiram Eldar, <a href="/A324708/b324708.txt">Table of n, a(n) for n = 1..1000</a>

%e 114 is in the sequence since it is the lesser of the amicable pair (114, 126): tsigma(114) = tsigma(126) = 114 + 126.

%t f[p_, e_] := If[e == 3, (p^4-1)/(p-1), If[e==6, (p^8-1)/(p^2-1), p^e+1]]; tsigma[1]=1; tsigma[n_]:= Times @@ f @@@ FactorInteger[n]; s[n_] := tsigma[n] - n; seq={}; Do[m=s[n]; If[m>n && s[m]==n, AppendTo[seq, n]] ,{n,1,700000}]; seq

%Y Cf. A002025, A002952, A126169, A292980, A322541, A324706, A324707, A324709.

%K nonn

%O 1,1

%A _Amiram Eldar_, Mar 11 2019