a(n) = (A000111(2*p) - 1)/(2*p), where p = A000040(n) = prime(n).

A180419

a(n) = (A000111(2*p) - 1)/(2*p), where p = A000040(n) = prime(n).

Terms

    a(0) =1a(1) =10a(2) =5052a(3) =14240070

External references