A049145 Revert transform of (1 + x - x^3)/(1 + 2x + 2x^2).

1, 1, 2, 4, 10, 26, 72, 205, 600, 1790, 5428, 16676, 51800, 162408, 513288, 1633543, 5230506, 16838080, 54465356, 176933606, 577002976, 1888274740, 6199187904, 20411160754, 67384417204, 223006818992, 739711312416, 2458778309456

Offset

1,3

Links

Table of n, a(n) for n=1..28.

Index entries for reversions of series

Formula

Recurrence: 23*(n-2)*(n-1)*n*(1952*n^4 - 27296*n^3 + 143698*n^2 - 337909*n + 300105)*a(n) = 6*(n-2)*(n-1)*(15616*n^5 - 241792*n^4 + 1475664*n^3 - 4388916*n^2 + 6235155*n - 3244875)*a(n-1) + 12*(n-2)*(19520*n^6 - 351040*n^5 + 2595700*n^4 - 10118262*n^3 + 21981753*n^2 - 25301906*n + 12089085)*a(n-2) - 8*(7808*n^7 - 167744*n^6 + 1499720*n^5 - 7198988*n^4 + 19849331*n^3 - 30868184*n^2 + 24125019*n - 6602040)*a(n-3) + 16*(n-4)*(n-2)*(1952*n^5 - 33152*n^4 + 232690*n^3 - 818047*n^2 + 1375383*n - 825255)*a(n-4) + 64*(n-5)*(n-4)*(2*n - 11)*(1952*n^4 - 19488*n^3 + 73522*n^2 - 124593*n + 80550)*a(n-5). - Vaclav Kotesovec, Jan 02 2021

Mathematica

Rest[CoefficientList[InverseSeries[Series[x*(1 + x - x^3)/(1 + 2x + 2x^2), {x, 0, 40}], x], x]] (* Vaclav Kotesovec, Jan 02 2021 *)

Crossrefs

Sequence in context: A075864 A180023 A154835 * A102407 A358455 A356832

Adjacent sequences: A049142 A049143 A049144 * A049146 A049147 A049148

Keyword

nonn

Author

Olivier Gérard

Status

approved