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A031399 Numbers n with no 4k+3 factors such that Pell equation x^2 - n y^2 = -1 insoluble. 1
4, 8, 16, 20, 25, 32, 34, 40, 52, 64, 68, 80, 100, 104, 116, 128, 136, 146, 148, 160, 164, 169, 178, 194, 200, 205, 208, 212, 221, 232, 244, 256, 260, 272, 289, 292, 296, 305, 320, 328, 340, 356, 377, 386, 388, 400, 404, 410, 416, 424, 436, 452 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

"Advanced Number Theory" by Harvey Cohn.

LINKS

Table of n, a(n) for n=1..52.

Joerg Arndt, Matters Computational (The Fxtbook)

CROSSREFS

Cf. A031396, A031397, A031398.

Sequence in context: A104235 A036993 A143718 * A312794 A312795 A312796

Adjacent sequences:  A031396 A031397 A031398 * A031400 A031401 A031402

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified November 12 19:33 EST 2019. Contains 329078 sequences. (Running on oeis4.)