A087781 Number of non-congruent solutions to x^2 - x - 1 == 0 mod n.

1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 2, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0

Offset: 1

Author

Yuval Dekel (dekelyuval(AT)hotmail.com), Oct 06 2003

Keywords

• mult
• nonn

Comments

Sequence A089270 gives the positions of the nonzero terms. The term a(n) gives the number of primitive solutions (x,y) of the equation x^2 + xy - y^2 = n.

Links

• T. D. Noe, Table of n, a(n) for n=1..10000

Crossrefs

Cf. A000086, A034444.

Extensions

More terms from David Wasserman, Jun 17 2005