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A031428 Numbers n such that least term in period of continued fraction for sqrt(n) is 4. 1
5, 18, 39, 68, 105, 150, 174, 203, 264, 333, 370, 410, 495, 588, 689, 793, 798, 855, 915, 1040, 1105, 1173, 1313, 1314, 1378, 1387, 1462, 1463, 1620, 1785, 1958, 2138, 2139, 2222, 2232, 2328, 2525, 2730, 2834, 2943, 3164, 3393, 3630, 3741 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 (first 700 from Vincenzo Librandi)

MATHEMATICA

Select[Range[4000], !IntegerQ[Sqrt[#]] && Min[ContinuedFraction[Sqrt[#]][[2]]] == 4&] (* Vincenzo Librandi, Feb 06 2012 *)

CROSSREFS

Different from A007742.

Sequence in context: A038346 A220243 A065007 * A007742 A225272 A276819

Adjacent sequences:  A031425 A031426 A031427 * A031429 A031430 A031431

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified May 10 05:05 EDT 2021. Contains 343748 sequences. (Running on oeis4.)