a(n) = |{(x_1, x_2, ... , x_n) : 1 <= x_1 <= x_2 <= ... <= x_n <= n, gcd(x_1, x_2, ... , x_n, n) = 1}|.

A343565

a(n) = |{(x_1, x_2, ... , x_n) : 1 <= x_1 <= x_2 <= ... <= x_n <= n, gcd(x_1, x_2, ... , x_n, n) = 1}|.

Terms

    a(0) =1a(1) =2a(2) =9a(3) =30a(4) =125a(5) =428a(6) =1715a(7) =6270a(8) =24255a(9) =91367a(10) =352715a(11) =1345448a(12) =5200299a(13) =20019526a(14) =77554749a(15) =300295038a(16) =1166803109a(17) =4535971916a(18) =17672631899a(19) =68913247655a(20) =269128640958

External references