a(n) = n^2 + n*floor(n*tau) - floor(n*tau)^2.

Terms

a(0) =0a(1) =1a(2) =1a(3) =5a(4) =4a(5) =1a(6) =9a(7) =5a(8) =16a(9) =11a(10) =4a(11) =19a(12) =11a(13) =1a(14) =20a(15) =9a(16) =31a(17) =19a(18) =5a(19) =31a(20) =16a(21) =45a(22) =29a(23) =11a(24) =44a(25) =25a(26) =4a(27) =41a(28) =19a(29) =59