a(n) is the least nonsquare having square residues modulo each of the first n primes.

Terms

a(0) =2a(1) =3a(2) =6a(3) =15a(4) =15a(5) =91a(6) =246a(7) =399a(8) =399a(9) =399a(10) =3045a(11) =3045a(12) =21099a(13) =41155a(14) =43059a(15) =182919a(16) =182919a(17) =182919a(18) =182919a(19) =860574a(20) =860574a(21) =8042479a(22) =8042479a(23) =11993466a(24) =11993466a(25) =11993466a(26) =78278655a(27) =78278655a(28) =78278655a(29) =78278655