a(n) is the number of n-digit positive integers with exactly three distinct base 10 digits.

A337313

a(n) is the number of n-digit positive integers with exactly three distinct base 10 digits.

Terms

    a(0) =0a(1) =0a(2) =648a(3) =3888a(4) =16200a(5) =58320a(6) =195048a(7) =625968a(8) =1960200a(9) =6045840a(10) =18468648a(11) =56068848a(12) =169533000a(13) =511252560a(14) =1539065448a(15) =4627812528a(16) =13904670600a(17) =41756478480a(18) =125354369448a(19) =376232977008

External references