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 A197121 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
 21, 69, 77, 84, 93, 133, 165, 189, 205, 213, 221, 237, 253, 276, 285, 301, 308, 309, 336, 341, 357, 372, 413, 429, 437, 453, 469, 501, 517, 525, 532, 581, 589, 597, 621, 645, 660, 669, 693, 717, 741, 749, 756, 789, 805, 820, 837, 852, 861, 869, 884, 893, 917 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers which occured in A087643 and not in A194366. LINKS Table of n, a(n) for n=1..53. 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: A123779 A123839 A180758 * A175461 A272627 A043339 Adjacent sequences: A197118 A197119 A197120 * A197122 A197123 A197124 KEYWORD nonn AUTHOR Artur Jasinski, Oct 10 2011 STATUS approved

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Last modified September 11 17:54 EDT 2024. Contains 375839 sequences. (Running on oeis4.)