id:A003640 - OEIS Search Results

Search: id:A003640

Displaying 1-1 of 1 results found.

page 1

Number of genera of quadratic field with discriminant -n.
(Formerly M0090)

+0
1

1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 2, 2, 2, 1, 1, 2, 2, 2, 2, 1, 1, 2, 1, 1, 1, 4, 2, 2, 2, 2, 1, 2, 1, 2, 2, 2, 2, 4, 2, 1, 1, 4, 2, 1, 2, 2, 1, 2, 2, 2, 1, 2, 1, 4, 1, 2, 2, 2, 1, 4, 1, 2, 1, 2, 2, 2, 1, 1, 4, 4, 2, 2, 1, 2, 2, 2, 1, 4, 2, 4, 1, 4, 2, 1, 4, 4, 1, 2, 2, 2, 2, 2, 2, 2, 1, 4, 1, 4, 2, 2, 2, 2, 1, 2 (list; graph; listen)

	OFFSET	`3,6`
	REFERENCES	`D. A. Buell, Binary Quadratic Forms. Springer-Verlag, NY, 1989, pp. 224-241.` `N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).`
	LINKS	`Index entries for sequences related to quadratic fields`
	FORMULA	`a(d) = 2^{t-1}, where t = number of distinct prime divisors of d.`
	CROSSREFS	`Sequence in context: A160978 A055734 A095772 this_sequence A107459 A087976 A117277` `Adjacent sequences: A003637 A003638 A003639 this_sequence A003641 A003642 A003643`
	KEYWORD	`nonn,easy,nice`
	AUTHOR	`N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein`

page 1

Search completed in 0.002 seconds

Last modified November 27 22:38 EST 2009. Contains 167602 sequences.

AT&T Labs Research