Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.

A000003

Number of classes of primitive positive definite binary quadratic forms of discriminant D = -4n; or equivalently the class number of the quadratic order of discriminant D = -4n.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =2a(6) =1a(7) =2a(8) =2a(9) =2a(10) =3a(11) =2a(12) =2a(13) =4a(14) =2a(15) =2a(16) =4a(17) =2a(18) =3a(19) =4a(20) =4a(21) =2a(22) =3a(23) =4a(24) =2a(25) =6a(26) =3a(27) =2a(28) =6a(29) =4

External references