Nonsquares mod 42.

Terms

a(0) =2a(1) =3a(2) =5a(3) =6a(4) =8a(5) =10a(6) =11a(7) =12a(8) =13a(9) =14a(10) =17a(11) =19a(12) =20a(13) =23a(14) =24a(15) =26a(16) =27a(17) =29a(18) =31a(19) =32a(20) =33a(21) =34a(22) =35a(23) =38a(24) =40a(25) =41