Nonnegative numbers n for which n^2 - n + 41 is not squarefree.
41, 604, 799, 891, 918, 1246, 1254, 1319, 1641, 1652, 1722, 2011, 2070, 2252, 2453, 2607, 2650, 3095, 3100, 3322, 3403, 3528, 3608, 4124, 4240, 4302, 4820, 4944, 5003, 5084, 5309, 5373, 5426, 5737, 5791, 5931, 5959, 5999, 6151, 6417, 6512, 6684, 6765
1
This quadratic is prime for n = 0..40. If we look at the differences of these numbers, it is clear that 81 is a common difference. Why? This is shown in S000162. The discriminant of this quadratic is 163, which is 2*81 + 1.
T. D. Noe, Plot of 1000 terms
T. D. Noe, Table of 1000 terms
Wikipedia, Formula for primes
(Mma) Select[Range[0, 10000], ! SquareFreeQ[#^2 - # + 41] &]
Cf. A202018 (n^2 + n + 41), S000160, S000161, S000162.
nonn
T. D. Noe, Jul 22 2014