a(n) = (3/5)*2^(4n+1) - (1/5).

A182460

a(n) = (3/5)*2^(4n+1) - (1/5).

Terms

    a(0) =1a(1) =19a(2) =307a(3) =4915a(4) =78643a(5) =1258291a(6) =20132659a(7) =322122547a(8) =5153960755a(9) =82463372083

External references