The number of symmetric positive definite 2 X 2 matrices whose entries are integers of absolute value at most n.

A219693

The number of symmetric positive definite 2 X 2 matrices whose entries are integers of absolute value at most n.

Terms

    a(0) =1a(1) =10a(2) =31a(3) =68a(4) =133a(5) =226a(6) =351a(7) =512a(8) =721a(9) =986a(10) =1303a(11) =1676a(12) =2125a(13) =2642a(14) =3231a(15) =3896a(16) =4665a(17) =5522a(18) =6479a(19) =7532a(20) =8701a(21) =9986a(22) =11383a(23) =12896a(24) =14553a(25) =16354a(26) =18287a(27) =20364a(28) =22605a(29) =24994

External references