A339678 Lesser of amicable pair (a, b) such that the sum of their number of divisors d(a) + d(b) sets a new record.
220, 1184, 6232, 10744, 12285, 67095, 69615, 522405, 1175265, 1798875, 4482765, 5730615, 9773505, 10634085, 34765731, 203972715, 211319745, 558410475, 1131258975, 2221700481, 3900906009, 4416880923, 9357224877, 36853129467, 139043711025, 200453238531, 200795248485
Offset: 1
Keywords
Examples
The least pair of amicable numbers, (220, 284), has a sum of numbers of divisors d(220) + d(284) = 12 + 6 = 18. The second pair, (1184, 1210) has a larger sum: d(1184) + d(1210) = 12 + 12 = 24. The next pair with a larger sum is (6232, 6368) whose sum is d(6232) + d(6368) = 16 + 12 = 28.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..55
- Sergei Chernykh, Amicable pairs list.
- Amiram Eldar, Table of n, a(n), A339679(n), A000005(a(n)) + A000005(A339679(n)) for n = 1..55
Programs
-
Mathematica
s[n_] := DivisorSigma[1, n] - n; dm = 0; seq = {}; Do[m = s[n]; If[m > n && s[m] == n && (d = Plus @@ DivisorSigma[0,{n, m}]) > dm, dm = d; AppendTo[seq, n]], {n,1 ,10^6}]; seq
Comments