A306868 Larger of augmented bi-unitary amicable pair.
871585, 1388145, 1483785, 2479065, 2580105, 4895241, 3830625, 7336455, 9100905, 10350345, 16933105, 9843526, 16367481, 24829945, 15706090, 18653745, 27866241, 21080865, 15439545, 23872185, 24401601, 32263905, 53763535, 63075321, 41337555, 60923577, 90245793
Offset: 1
Keywords
Examples
871585 is in the sequence since it is the larger of the amicable pair (434784, 871585): bsigma(434784) = bsigma(871585) = 1306368 = 434784 + 871585 - 1.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..509 (terms with lesser member below 2*10^11, from David Moews's site).
- David Moews, Perfect, amicable and sociable numbers.
Programs
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Mathematica
fun[p_, e_]:=If[OddQ[e], (p^(e+1)-1)/(p-1), (p^(e+1)-1)/(p-1)-p^(e/2)]; bsigma[1] = 1; bsigma[n_] := Times @@ (fun @@@ FactorInteger[n]); f[n_] := bsigma[n] - n + 1; s={}; Do[m = f[n]; If[m > n && f[m] == n, AppendTo[s, m]], {n, 1, 10^7}]; s
Comments