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 A013648 Numbers n such that period of continued fraction for sqrt(n) contains a single 1. 4
 3, 8, 15, 24, 35, 48, 63, 80, 99, 120, 143, 168, 175, 176, 195, 208, 224, 255, 288, 323, 360, 399, 440, 483, 528, 551, 575, 624, 675, 728, 783, 799, 840, 899, 960, 1023, 1035, 1088, 1155, 1224, 1247, 1295, 1368, 1403, 1443, 1520, 1599, 1680, 1763, 1848, 1872 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS All the terms of A005563 are here, as well as some additional terms (with even period > 2 and the digit 1 in central position) (e.g. sqrt(175) = [13,'4, 2, 1, 2, 4, 26']). REFERENCES Kenneth H. Rosen, Elementary Number Theory and Its Applications, Addison-Wesley, 1984, page 426 (but beware of errors!). LINKS T. D. Noe, Table of n, a(n) for n = 1..1000 R. Macmillan, Continued fractions, Math. Gaz. 84, 2000. See p. 34. FORMULA Union of A005563 and A102538. MATHEMATICA Select[ Range@ 1900, !IntegerQ[ Sqrt@ #] && Count[ ContinuedFraction[ Sqrt@ #][[2]], 1] == 1 &] (* Robert G. Wilson v, Jul 03 2011 *) CROSSREFS Cf. A040001, A040005, A040011, A040019, A040029, A062196. Sequence in context: A086959 A335753 A083656 * A258837 A131386 A132411 Adjacent sequences:  A013645 A013646 A013647 * A013649 A013650 A013651 KEYWORD nonn AUTHOR EXTENSIONS Additional comments from Francisco Salinas (franciscodesalinas(AT)hotmail.com), Dec 30 2001 Incorrect formulas and programs removed - R. J. Mathar, Jan 06 2011 STATUS approved

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Last modified August 3 08:10 EDT 2020. Contains 336197 sequences. (Running on oeis4.)