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A106030
a(n) is the number of orbits under the action of GL_2[Z] on the primitive binary quadratic forms of discriminant D, where D=m if m=1 (mod 4), D=4*m otherwise and m>1 is the n-th squarefree number.
1
1, 2, 1, 2, 2, 2, 2, 1, 2, 4, 1, 2, 2, 2, 2, 2, 1, 4, 2, 2, 3, 4, 1, 2, 4, 1, 4, 2, 2, 2, 4, 1, 4, 2, 2, 2, 1, 2, 2, 4, 2, 2, 4, 2, 1, 2, 2, 4, 4, 3, 2, 2, 2, 4, 1, 4, 2, 2, 4, 1
OFFSET
1,2
COMMENTS
A104888 is the same except it is under the action of SL_2[Z].
LINKS
S. R. Finch, Class number theory
Steven R. Finch, Class number theory [Cached copy, with permission of the author]
Jens Jonasson, Classes of integral binary quadratic forms, Master's thesis (2001), Appendix B.
EXAMPLE
m = 2, 3, 5, 6, 7, 10, 11, 13, 14, 15, 17, ...
with corresponding discriminant
D = 8, 12, 5, 24, 28, 40, 44, 13, 56, 60, 17, ....
CROSSREFS
Cf. A104888.
Sequence in context: A055255 A057768 A317990 * A104888 A286885 A365618
KEYWORD
nonn
AUTHOR
Steven Finch, May 05 2005
STATUS
approved