A176836 Number of pairs (a, b) of positive integers with a <= b such that both a^2 - nb and b^2 - na are squares

1, 1, 4, 2, 6, 4, 8, 7, 12, 6, 10, 15, 14, 8, 26, 21, 16, 12, 16, 30, 32

Offset

1,3

Links

Table of n, a(n) for n=1..21.

Example

a(4) = 2 because the pairs (4, 4) and (5, 6) have the specified property: 4^4 - 4*4 = 0^2; 5^2 - 4*6 = 1^2, 6^2 - 4*5 = 4^2.

Crossrefs

a(n) = A176835(n) + A176837(n)

Sequence in context: A200697 A253629 A327095 * A329287 A368665 A372529

Adjacent sequences: A176833 A176834 A176835 * A176837 A176838 A176839

Keyword

nonn

Author

Jens Voß, Apr 27 2010

Status

approved