Squares mod 84.

Terms

a(0) =0a(1) =1a(2) =4a(3) =9a(4) =16a(5) =21a(6) =25a(7) =28a(8) =36a(9) =37a(10) =49a(11) =57a(12) =60a(13) =64a(14) =72a(15) =81