1,13

A271910(n) = A272624(n) + a(n) + A272626(n).

Chai Wah Wu, Table of n, a(n) for n = 1..3003

Chai Wah Wu, Counting the number of isosceles triangles in rectangular regular grids, arXiv:1605.00180 [math.CO], 2016.

T(n,k) = 3*T(n,k-1)-3*T(n,k-2)+T(n,k-3) for k > (n-1)^2+1.

Cf. A271910, A272624, A272626.

Sequence in context: A306756 A079204 A325737 * A220667 A317445 A199619

Adjacent sequences: A272622 A272623 A272624 * A272626 A272627 A272628

nonn,tabl

Chai Wah Wu, May 07 2016

approved