Number of distinct characteristic polynomials for 2 X 2 matrices with entries from {0, 1, ..., n}.

Terms

a(0) =1a(1) =6a(2) =22a(3) =58a(4) =116a(5) =221a(6) =356a(7) =573a(8) =824a(9) =1163a(10) =1565a(11) =2143a(12) =2697a(13) =3527a(14) =4385a(15) =5388a(16) =6455a(17) =7992a(18) =9342a(19) =11262a(20) =12953a(21) =15034a(22) =17301a(23) =20246a(24) =22595a(25) =25823a(26) =29054a(27) =32679a(28) =36228a(29) =41112