First differences of numbers n for which n^2 - n + 41 is not squarefree (S000159).
563, 195, 92, 27, 328, 8, 65, 322, 11, 70, 289, 59, 182, 201, 154, 43, 445, 5, 222, 81, 125, 80, 516, 116, 62, 518, 124, 59, 81, 225, 64, 53, 311, 54, 140, 28, 40, 152, 266, 95, 172, 81, 28, 580, 145, 111, 317, 54, 55, 77, 24, 100, 109, 81, 196, 388, 64, 71, 61
1
Note that 81 occurs more than any other number. Why?
T. D. Noe, Plot of 10000 terms
T. D. Noe, Table of 10000 terms
(Mma) Differences[Select[Range[20000], ! SquareFreeQ[#^2 - # + 41] &]]
Cf. S000159.
nonn
T. D. Noe, Jul 22 2014