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A097917 Denominator of 2*zeta_K(-1) where K is the totally real field Q(sqrt(n)), as n runs through the squarefree numbers. 3
6, 3, 15, 1, 3, 3, 3, 3, 3, 1, 3, 3, 3, 3, 3, 3, 1, 3, 3, 1, 3, 3, 3, 3, 3, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

F. Hirzebruch, Hilbert modular surfaces, Ges. Abh. II, 225-323.

LINKS

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

F. Hirzebruch, Hilbert modular surfaces, L'Enseignement Math., 19 (1973), 183-281. See p. 200.

EXAMPLE

1/6, 1/3, 1/15, 1, 4/3, 7/3, 7/3, 1/3, 10/3, 4, ...

CROSSREFS

Cf. A097916.

Sequence in context: A345056 A049784 A341746 * A116570 A335567 A225503

Adjacent sequences:  A097914 A097915 A097916 * A097918 A097919 A097920

KEYWORD

nonn,frac,more

AUTHOR

N. J. A. Sloane, Sep 04 2004

STATUS

approved

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Last modified July 29 02:27 EDT 2021. Contains 346340 sequences. (Running on oeis4.)