Composite numbers k such that phi(k) * psi(k) + 1 is a perfect square, where phi is the Euler totient function (A000010) and psi is the Dedekind psi function (A001615).
A309653
Composite numbers k such that phi(k) * psi(k) + 1 is a perfect square, where phi is the Euler totient function (A000010) and psi is the Dedekind psi function (A001615).
Terms
- a(0) =6a(1) =8a(2) =20a(3) =22a(4) =33a(5) =69a(6) =82a(7) =156a(8) =171a(9) =190a(10) =198a(11) =295a(12) =354a(13) =451a(14) =581a(15) =664a(16) =1119a(17) =1142a(18) =1175a(19) =1184a(20) =2812a(21) =2893a(22) =4043a(23) =4163a(24) =4262a(25) =4581a(26) =5090a(27) =6964a(28) =7018a(29) =12977
External references
- oeis: A309653