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A249021 Value x in the solution of x^2-D*y^2=-1 as D runs through A003654. 2
7, 38, 117, 18, 268, 515, 70, 882, 32, 182, 99, 29718, 2072, 1068, 43, 2943, 378, 500, 5604, 4030, 4005, 8890182, 776, 5357, 57, 1744, 6948, 113582, 4832118, 8827, 1118, 1111225770, 68, 1764132, 11018, 3141, 251, 13545, 1710, 23156, 71011068, 16432, 6072, 82, 1407, 8920484118, 1063532, 19703 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The pair (x,y) is taken from the numerator of the earliest (lowest order) convergent to the continued fraction of sqrt(D) that satisfies the "non-Pell" equation.

LINKS

Table of n, a(n) for n=1..48.

MAPLE

A249021 := proc(n)

    local dis, cf, o, q, x, y ;

    dis := A003654(n) ;

    cf := numtheory[cfrac](sqrt(dis), 'periodic', 'quotients') ;

    for o from 1 do

        q := numtheory[nthconver](cf, o) ;

        x := numer(q) ;

        y := denom(q) ;

        if x^2-dis*y^2 = -1 then

            return x ;

        end if;

    end do:

end proc:

seq(A249021(n), n=1..50) ;

CROSSREFS

Cf. A130226.

Sequence in context: A165495 A034858 A249354 * A114290 A277912 A000531

Adjacent sequences:  A249018 A249019 A249020 * A249022 A249023 A249024

KEYWORD

nonn

AUTHOR

R. J. Mathar, Oct 19 2014

STATUS

approved

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Last modified April 22 12:53 EDT 2021. Contains 343177 sequences. (Running on oeis4.)