Odd numbers k such that sigma(k) > 2*k and A003415(sigma(k)) < k, where A003415 is the arithmetic derivative, and sigma is the sum of divisors function.
A347890
Odd numbers k such that sigma(k) > 2*k and A003415(sigma(k)) < k, where A003415 is the arithmetic derivative, and sigma is the sum of divisors function.
Terms
- a(0) =245025a(1) =540225a(2) =893025a(3) =2205225a(4) =3080025a(5) =4862025a(6) =6125625a(7) =6890625a(8) =7868025a(9) =10989225a(10) =13505625a(11) =14402025a(12) =19847025a(13) =22896225a(14) =23474025a(15) =26471025a(16) =27720225a(17) =29648025a(18) =43758225a(19) =45765225a(20) =55130625a(21) =57836025a(22) =60140025a(23) =65367225a(24) =70812225a(25) =72335025a(26) =76475025a(27) =77000625a(28) =94770225a(29) =121550625
External references
- oeis: A347890