A031412 Numbers k such that the continued fraction for sqrt(k) has even period 2*m and the m-th term of the periodic part is 9.

83, 103, 107, 119, 328, 352, 384, 416, 424, 480, 735, 795, 807, 879, 951, 1011, 1083, 1304, 1432, 1496, 1544, 1688, 1816, 1928, 2035, 2215, 2315, 2335, 2435, 2515, 2535, 2615, 2735, 2815, 2928, 2935, 3015, 3216, 3768, 3792, 3983, 4056, 4344, 4375, 4627

Offset

1,1

Links

T. D. Noe, Table of n, a(n) for n = 1..1000

Mathematica

n = 1; t = {}; While[Length[t] < 50, n++; If[! IntegerQ[Sqrt[n]], c = ContinuedFraction[Sqrt[n]]; len = Length[c[[2]]]; If[EvenQ[len] && c[[2, len/2]] == 9, AppendTo[t, n]]]]; t (* T. D. Noe, Apr 04 2014 *)

Crossrefs

Cf. A031404-A031423.

Sequence in context: A139965 A180523 A139765 * A033252 A347226 A261449

Adjacent sequences: A031409 A031410 A031411 * A031413 A031414 A031415

Keyword

nonn

Author

David W. Wilson

Status

approved