The number of 2 X 2 symmetric positive definite matrices whose entries are integers x,y,z satisfying x^2 + y^2 + z^2 <= n^2.
A219744
The number of 2 X 2 symmetric positive definite matrices whose entries are integers x,y,z satisfying x^2 + y^2 + z^2 <= n^2.
Terms
- a(0) =0a(1) =1a(2) =10a(3) =22a(4) =49a(5) =92a(6) =150a(7) =227a(8) =328a(9) =449a(10) =609a(11) =792a(12) =1017a(13) =1281a(14) =1582a(15) =1911a(16) =2308a(17) =2750a(18) =3241a(19) =3778a(20) =4420a(21) =5049a(22) =5776a(23) =6572a(24) =7429a(25) =8378a(26) =9413a(27) =10505a(28) =11646a(29) =12935
External references
- oeis: A219744