|
| |
|
|
A006643
|
|
Class number of quadratic field with discriminant -4n as n runs through squarefree numbers congruent to 1 or 2 mod 4.
(Formerly M0225)
|
|
1
| |
|
|
1, 1, 2, 2, 2, 2, 4, 4, 4, 2, 6, 6, 4, 4, 4, 2, 6, 8, 4, 4, 6, 4, 2, 6, 8, 8, 8, 8, 4, 4, 10, 8, 4, 4, 4, 10, 12, 4, 8, 4, 14, 4, 8, 6, 6, 12, 8, 8, 6, 10, 12, 4, 4, 14, 8, 8, 8, 4, 8, 16, 14, 8, 6, 8, 16, 8, 10, 12, 14, 12, 4, 8, 10, 12, 16, 12, 4, 4, 20, 10, 12, 6, 8, 20, 20, 8, 8, 6, 8, 10, 16
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,3
|
|
|
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).
|
|
|
CROSSREFS
| Cf. A006642.
Sequence in context: A074912 A158502 A195427 * A080217 A157901 A072376
Adjacent sequences: A006640 A006641 A006642 * A006644 A006645 A006646
|
|
|
KEYWORD
| nonn
|
|
|
AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Mira Bernstein (mira(AT)math.berkeley.edu)
|
|
|
EXTENSIONS
| Extended and definition corrected by Max Alekseyev (maxale(AT)gmail.com), Apr 16 2010
|
| |
|
|
