A006371 Number of reduced binary quadratic forms of discriminant -n. (Formerly M0207)

1, 1, 1, 1, 1, 2, 2, 2, 1, 2, 3, 2, 2, 2, 3, 3, 2, 3, 4, 2, 1, 4, 5, 4, 2, 2, 4, 4, 3, 4, 5, 4, 1, 4, 7, 3, 3, 4, 5, 6, 3, 4, 6, 2, 2, 6, 8, 6, 3, 3, 5, 6, 3, 6, 8, 4, 2, 6, 10, 4, 2, 6, 5, 7, 5, 4, 8, 4, 3, 8, 10, 8, 3, 2, 7, 6, 4, 8, 10, 6, 1, 8

Offset

3,6

References

H. Davenport, The Higher Arithmetic. Cambridge Univ. Press, 5th edition, 1982, p. 144.

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

Table of n, a(n) for n=3..84.

Rick L. Shepherd, Binary quadratic forms and genus theory, Master of Arts Thesis, University of North Carolina at Greensboro, 2013.

Crossrefs

Cf. A006374.

Sequence in context: A182597 A290491 A194314 * A000177 A319815 A222656

Adjacent sequences: A006368 A006369 A006370 * A006372 A006373 A006374

Keyword

nonn

Author

N. J. A. Sloane

Extensions

More terms from Sean A. Irvine, Mar 19 2017

Status

approved