A055139 Column 0 of triangle A055138.
1, -1, 0, 1, -1, -1, 4, -1, -19, 31, 120, -483, -933, 8623, 6748, -189589, 41561, 5147391, -6328400, -170622599, 394612599, 6807529823, -23890335372, -322371010985, 1564733285829, 17884889743135, -114158790326872
Offset: 0