A187278 The radical part of the expression whose continued fraction has periodic part 1..n.

5, 3, 37, 156, 65029, 66736, 29964677, 121445910, 635918528029, 640952674263, 1951254635768065, 7846010029748338, 191780091068145774653, 192496359548972143176, 2129087866550404672890001, 2135029389612694590809079, 633378381185791927931233429813, 70527645518718791726538220475

Offset

1,1

Links

G. C. Greubel, Table of n, a(n) for n = 1..252

Example

a(1) = 5 because the cf of (-1+sqrt(5))/2 is {0, {1}}, that part in the second parenthesis is reoccurring,
a(2) = 3 because the cf of -1 + Sqrt(3) is {0, {1, 2}},
a(3) = 37 because the cf of (-4+Sqrt(37))/3 is {0, {1, 2, 3}}, etc.

Mathematica

f[n_] := (FromContinuedFraction[{0, Range@ n}][[-1, -1]])^2; Array[ f, 16]

Crossrefs

Sequence in context: A279066 A179210 A291843 * A288184 A323779 A343290

Adjacent sequences: A187275 A187276 A187277 * A187279 A187280 A187281

Keyword

nonn

Author

Robert G. Wilson v, Mar 07 2011

Status

approved