Sigma-powerful numbers: powerful numbers n such that sigma(n) is also powerful. An incomplete version of A337045.

A180090

Sigma-powerful numbers: powerful numbers n such that sigma(n) is also powerful. An incomplete version of A337045.

Terms

    a(0) =81a(1) =343a(2) =400a(3) =1705636a(4) =3648100a(5) =13645088a(6) =25992000a(7) =26680500a(8) =29184800a(9) =80802000a(10) =110215125a(11) =178054848a(12) =180093375a(13) =213444000a(14) =310144500a(15) =408632609a(16) =575664500a(17) =1055340196a(18) =1120504500a(19) =1476326929a(20) =1667329664a(21) =2066544500

External references