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A212074
Beach-Williams Pell numbers of type 2p (p prime).
10
3202, 3554, 6178, 6274, 6626, 7522, 8354, 9442, 9634, 12706, 12962, 14978, 15586, 16418, 16546, 18754, 19298, 22114, 24098, 24482
OFFSET
1,1
COMMENTS
Consider the problem of finding all integers n such that the Pell equation x^2 - n*y^2 = -1 is solvable in integers x,y with y != 0. Beach and Williams found that there are 102662 such values of n in the range 1 <= n <= 10^6.
Of these, 3531 "exceptional" values of n were not predicted by a certain list of criteria given in their paper. These 3531 exceptional values fall into 10 classes given in sequences A212074-A212083.
REFERENCES
Beach, B. D. and Williams, H. C., A numerical investigation of the Diophantine equation x^2-dy^2=-1. Proceedings of the Third Southeastern Conference on Combinatorics, Graph Theory and Computing (Florida Atlantic Univ., Boca Raton, Fla., 1972), pp. 37-68. Florida Atlantic Univ., Boca Raton, Fla., 1972.
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Apr 30 2012
STATUS
approved