The number of 2 X 2 matrices with all eigenvalues real and whose entries are integers with absolute value at most n.

A219736

The number of 2 X 2 matrices with all eigenvalues real and whose entries are integers with absolute value at most n.

Terms

    a(0) =67a(1) =477a(2) =1759a(3) =4729a(4) =10395a(5) =20141a(6) =35423a(7) =58225a(8) =90579a(9) =134813a(10) =193503a(11) =269785a(12) =366267a(13) =486925a(14) =635199a(15) =815105a(16) =1030371a(17) =1286221a(18) =1586447a(19) =1937033a(20) =2342379a(21) =2808221a(22) =3340239a(23) =3945361a(24) =4628467a(25) =5396781a(26) =6257039a(27) =7216457a(28) =8281579a(29) =9461805

External references