A078146 - OEIS

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A078146

Length of period of continued fraction for square root of -1 + n!.

1

0, 0, 1, 4, 4, 28, 4, 12, 64, 600, 380, 10908, 23720, 168072, 5924, 1643064, 1896378, 685042, 16089346, 695623764, 722967470, 6166991370, 18958904524, 248206315456, 644968837504, 1200298458074

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OFFSET

1,4

LINKS

Table of n, a(n) for n=1..26.

FORMULA

a(n) = A003285(A033312(n)). - Michel Marcus, Sep 25 2019

EXAMPLE

Period for sqrt(4!-1) = sqrt(23) = {1,1,1,4}, a(4) = 4.

MATHEMATICA

Table[Length[Last[ContinuedFraction[Sqrt[ -1+n! ]]]], {n, 1, 14}]

CROSSREFS

Cf. A003285, A033312, A078145, A064025.

Sequence in context: A132650 A112953 A110139 * A066836 A227715 A173049

Adjacent sequences: A078143 A078144 A078145 * A078147 A078148 A078149

KEYWORD

nonn,more,hard

AUTHOR

Labos Elemer, Nov 25 2002

EXTENSIONS

a(15)-a(21) from Amiram Eldar, Aug 28 2019

a(22)-a(23) from Chai Wah Wu, Sep 24 2019

a(24)-a(26) from Chai Wah Wu, Sep 30 2019

STATUS

approved