Numbers m = concat(s,t) such that m = sigma(s) * sigma(t), where sigma(x) is the sum of the divisors of x.
A253824
Numbers m = concat(s,t) such that m = sigma(s) * sigma(t), where sigma(x) is the sum of the divisors of x.
Terms
- a(0) =540a(1) =2352a(2) =28224a(3) =82890a(4) =737856a(5) =1524096a(6) =1531152a(7) =3429216a(8) =17062920a(9) =22264200a(10) =23268600a(11) =49447728a(12) =104941200a(13) =162496048a(14) =197499456a(15) =267450144a(16) =502334784a(17) =619672032a(18) =2347826040a(19) =2942021520a(20) =4045874976a(21) =4302305280a(22) =9876226752a(23) =22712348160a(24) =24705882348a(25) =33114541824a(26) =34144545792a(27) =45916416000
External references
- oeis: A253824