a(n) = phi(9^n+1), where phi is Euler's totient function (A000010).
A366667
a(n) = phi(9^n+1), where phi is Euler's totient function (A000010).
Terms
- a(0) =1a(1) =4a(2) =40a(3) =288a(4) =3072a(5) =23600a(6) =259200a(7) =1847104a(8) =21523360a(9) =152845056a(10) =1700870400a(11) =12550120000a(12) =130459631616a(13) =997562438080
External references
- oeis: A366667