A306875 Lesser of reduced unitary amicable pair.
172622505, 6217560734, 16017860054, 18102483014, 20021589510, 31285993970, 32576024810, 39270110990, 68700877014, 80170395410, 81142298930, 99542647490, 125182657005, 144194617490, 153113328654, 181335043274, 318710758730, 374642686418, 378482712530, 455440763414
Offset: 1
Keywords
Examples
172622505 is in the sequence since it is the lesser of the amicable pair (172622505, 175742294): usigma(172622505) = usigma(175742294) = 348364800 = 172622505 + 175742294 + 1.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..28 (terms below 10^12, from David Moews's site).
- David Moews, Perfect, amicable and sociable numbers
- J. O. M. Pedersen, Tables of Aliquot Cycles
Programs
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Mathematica
us[n_] := Times @@ (1 + Power @@@ FactorInteger[n]) - n; s={}; Do[m = us[n] - 1; If[m > n && us[m] == n + 1, AppendTo[s, n]], {n, 1, 10^9}]; s
Comments