A064486 Period of continued fraction for square roots of primorials.

1, 2, 2, 2, 2, 4, 2, 36, 38, 244, 244, 1830, 3422, 10626, 3828, 20970, 580384, 4197850, 18395762, 76749396, 166966158, 1492773346, 2307891442, 30021987038, 150709818548, 20897087728

Offset

1,2

Links

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

Formula

a(n) = A003285(A002110(n)). - Michel Marcus, Sep 26 2019

Example

n=6: cfrac(sqrt(30030),'periodic','quotients')=[[173], [3, 2, 3, 346]], so a(6)=4

Maple

with(numtheory): [seq(nops(cfrac(sqrt(product(ithprime(j), j=1..k)), 'periodic', 'quotients')[2]), k=1..14)];

Mathematica

Table[Length[Part[ContinuedFraction[Sqrt[q[u]]], 2]], {u, 1, 18}]

Crossrefs

Cf. A002110, A003285.

Sequence in context: A153436 A354359 A367130 * A153437 A023153 A023159

Adjacent sequences: A064483 A064484 A064485 * A064487 A064488 A064489

Keyword

nonn,more

Author

Labos Elemer, Oct 04 2001

Extensions

a(19)-a(22) from Daniel Suteu, Jan 24 2019

a(23)-a(24) from Chai Wah Wu, Sep 25 2019

a(25)-a(26) from Chai Wah Wu, Sep 26 2019

Status

approved