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A014046 Second coordinate of fundamental unit of real quadratic field. 4
1, 1, 1, 1, 2, 1, 2, 3, 1, 8, 2, 1, 10, 3, 1, 4, 40, 1, 5, 2, 3, 250, 39, 1, 1, 42, 106, 5, 3, 1138, 2, 1, 8, 25, 146, 2, 273, 2968, 15, 6, 298, 1, 16, 2, 5, 6, 4, 17, 1856, 1, 2, 531, 1, 9384, 97, 3588, 10, 7, 253970, 2, 72664, 7, 3, 6440, 5, 521904, 12, 1, 1, 13 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

See A014000 for much more about this sequence. - N. J. A. Sloane, Jun 14 2013

REFERENCES

H. Cohen, A Course in Computational Alg. No. Theory, Springer, 1993, pp. 515-519.

LINKS

Table of n, a(n) for n=1..70.

S. R. Finch, Class number theory

PROG

(PARI) lista(nn) = { for (n=2, nn, if (isfundamental(n), nc = core(n); m = Mod (nc, 4); if ((m == 2) || (m == 3), d = 1); if ((m == 1), d = 4); b = 1; a = 0; while (a == 0, v = nc*b^2; if (issquare(v-d), a = sqrtint(v-d), if (issquare(v+d), a = sqrtint(v+d))); if (a == 0, b++; ); ); print1(b, ", "); ); ); } \\ Michel Marcus, Sep 25 2018

CROSSREFS

Cf. A014000.

Sequence in context: A008313 A232177 A111377 * A243919 A231775 A128065

Adjacent sequences:  A014043 A014044 A014045 * A014047 A014048 A014049

KEYWORD

nonn

AUTHOR

Eric Rains (rains(AT)caltech.edu)

STATUS

approved

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Last modified October 24 00:04 EDT 2018. Contains 316541 sequences. (Running on oeis4.)