A323759 - OEIS

%I #15 Feb 18 2019 05:30:09

%S 126,378,1260,3780,4584,5544,11424,16632,16728,49308,68760,73962,

%T 88608,179118,168730,212160,225096,256338,266568,250920,365700,374304,

%U 391656,374418,387720,386568,393528,548550,827700,739620,827652,932100,912288,935400,1052088

%N Larger of modified exponential amicable pairs.

%C A modified exponential amicable pair (m, n) has A241405(m) = A241405(n) = m + n + 1.

%C The lesser counterparts are in A323758.

%H Amiram Eldar, <a href="/A323759/b323759.txt">Table of n, a(n) for n = 1..4725</a> (terms whose lesser counterparts below 2*10^11)

%H David Moews, <a href="http://djm.cc/amicable.html">Perfect, amicable and sociable numbers</a>.

%t f[p_, e_] := DivisorSum[e+1, p^(#-1)&]; mesigma[1]=1; mesigma[n_] := Times @@ f @@@FactorInteger@ n; s={}; mes[n_] := mesigma[n]-n; Do[m=mes[n]; If[m>n && mes[m]==n, AppendTo[s, m]], {n,1,10000}]; s

%o (PARI) f(n) = {my(f=factor(n)); prod(i=1, #f[, 1], sumdiv(f[i, 2]+1, d, f[i, 1]^(d-1)));} \\ A241405

%o fm(n) = f(n) - n;

%o isok(n) = my(fn=fm(n)); (fn > 0) && (fn < n) && (fm(fn) == n); \\ _Michel Marcus_, Jan 30 2019

%Y Cf. A241405, A323757, A323758.

%K nonn

%O 1,1

%A _Amiram Eldar_, Jan 26 2019