a(n) = phi(10^n-1), where phi is Euler's totient function (A000010).

A295503

a(n) = phi(10^n-1), where phi is Euler's totient function (A000010).

Terms

    a(0) =6a(1) =60a(2) =648a(3) =6000a(4) =64800a(5) =466560a(6) =6637344a(7) =58752000a(8) =648646704a(9) =5890320000a(10) =66663457344a(11) =461894400000

External references