A369729 Number of solutions to +- 1 +- 3 +- 5 +- 7 +- ... +- (4*n-3) = 1.

0, 1, 1, 2, 5, 13, 38, 118, 380, 1262, 4277, 14745, 51541, 182182, 650095, 2338706, 8472697, 30884150, 113189168, 416839177, 1541726967, 5724470097, 21330062502, 79733319862, 298922247363, 1123678419818, 4234465089737, 15993581636893, 60535561889465

Offset

0,4

Links

Table of n, a(n) for n=0..28.

Formula

a(n) = [x^1] Product_{k=1..2*n-1} (x^(2*k-1) + 1/x^(2*k-1)).

Mathematica

Table[Coefficient[Product[(x^(2 k - 1) + 1/x^(2 k - 1)), {k, 1, 2 n - 1}], x, 1], {n, 0, 27}]

Crossrefs

Cf. A005408, A063866, A156700, A292476, A367087.

Sequence in context: A001475 A360271 A343937 * A149858 A148303 A148304

Adjacent sequences: A369726 A369727 A369728 * A369730 A369731 A369732

Keyword

nonn

Author

Ilya Gutkovskiy, Jan 30 2024

Status

approved