a(n) is the Euler totient function of the concatenation of 1,2,3,...,n.

A366955

a(n) is the Euler totient function of the concatenation of 1,2,3,...,n.

Terms

    a(0) =1a(1) =4a(2) =80a(3) =616a(4) =6576a(5) =41088a(6) =1224720a(7) =4027392a(8) =82260072a(9) =4938271560a(10) =635485074048

External references