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A187278 The radical part of the expression whose continued fraction has periodic part 1..n. 1
5, 3, 37, 156, 65029, 66736, 29964677, 121445910, 635918528029, 640952674263, 1951254635768065, 7846010029748338, 191780091068145774653, 192496359548972143176, 2129087866550404672890001, 2135029389612694590809079, 633378381185791927931233429813, 70527645518718791726538220475 (list; graph; refs; listen; history; text; internal format)
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 A027858

Adjacent sequences:  A187275 A187276 A187277 * A187279 A187280 A187281

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Mar 07 2011

STATUS

approved

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Last modified July 23 14:24 EDT 2019. Contains 325254 sequences. (Running on oeis4.)