A195550 - OEIS

A195550

Denominators a(n) of Pythagorean approximations b(n)/a(n) to 3/2.

3, 60, 660, 3597, 78480, 856080, 4669203, 101866380, 1111191780, 6060621597, 132222483360, 1442326073760, 7866682164003, 171624681534300, 1872138132549300, 10210947388253997, 222768704409038640, 2430033853722917040

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OFFSET

1,1

COMMENTS

See A195500 for a discussion and references.

LINKS

Table of n, a(n) for n=1..18.

MATHEMATICA

r = 3/2; z = 21;

p[{f_, n_}] := (#1[[2]]/#1[[

1]] &)[({2 #1[[1]] #1[[2]], #1[[1]]^2 - #1[[

2]]^2} &)[({Numerator[#1], Denominator[#1]} &)[

Array[FromContinuedFraction[

ContinuedFraction[(#1 + Sqrt[1 + #1^2] &)[f], #1]] &, {n}]]]];

{a, b} = ({Denominator[#1], Numerator[#1]} &)[

p[{r, z}]] (* A195550, A195551 *)

Sqrt[a^2 + b^2] (* A195552 *)

(* Peter J. C. Moses, Sep 02 2011 *)

CROSSREFS

Cf. A195500, A195551, A195552.

Sequence in context: A002738 A006432 A360577 * A377677 A144659 A115490

Adjacent sequences: A195547 A195548 A195549 * A195551 A195552 A195553

KEYWORD

nonn,frac

AUTHOR

Clark Kimberling, Sep 21 2011

STATUS

approved