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A197120 Nonsquare positive integers n such that the fundamental unit of quadratic field Q(sqrt(d))has norm -1 and minimum one from two parts of fundamental unit are not integer. 0
5, 13, 20, 29, 45, 52, 53, 61, 80, 85, 109, 116, 117, 125, 149, 157, 173, 180, 181, 208, 212, 229, 244, 245, 261, 277, 293, 317, 320, 325, 340, 365, 397, 405, 421, 436, 445, 461, 464, 468, 477, 493, 500, 509, 533, 541, 549, 565, 596, 605, 613, 628, 629, 637 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Numbers which occured in A172000 and not in A197115.

LINKS

Table of n, a(n) for n=1..54.

MATHEMATICA

cr = {}; Do[ If[IntegerQ[Sqrt[n]], , kk = NumberFieldFundamentalUnits[Sqrt[n]]; d1 = kk[[1]][[2]][[1]]; d2 = kk[[1]][[1]] kk[[1]][[2]][[2]]; d3 = Expand[(d1 + d2) (d1 - d2)]; If[d3 == -1, k1 = Max[Denominator[d1], Denominator[d2]]; If[k1 == 1, , AppendTo[cr, n]]]], {n, 2, 2000}]; cr

CROSSREFS

Cf. A087643, A172000, A194366, A197115.

Sequence in context: A184825 A190372 A184837 * A319449 A030374 A007675

Adjacent sequences:  A197117 A197118 A197119 * A197121 A197122 A197123

KEYWORD

nonn

AUTHOR

Artur Jasinski, Oct 10 2011

STATUS

approved

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Last modified December 12 07:31 EST 2019. Contains 329948 sequences. (Running on oeis4.)