A309254 Shifts left by 2 places under series reversion.

1, 1, 1, -1, 1, 1, -11, 41, -83, -77, 1621, -8503, 25689, -11283, -436307, 3380827, -15378675, 37938353, 87204085, -1755462619, 12722279385, -61250294425, 164643256457, 465385122833, -10366591960879, 88472237039417, -527994960273655, 2118908595206935, -1118896610239543

Offset: 1

Author

Vladimir Reshetnikov, Aug 07 2019

Keywords

• sign

Comments

Series reversion of the g.f. gives the same sequence with two initial terms (1, 1) dropped.

Crossrefs

Cf. A067145, A309564.

Programs

Mathematica

Nest[InverseSeries[#] x^2 + x^2 + x &, x + O[x]^2, 14][[3]]

Formula

G.f. satisfies A((A(x) - x - x^2)/x^2) = x.