A049142 Revert transform of (1 - x + 2x^2 - x^3)/(1 + 2x^2).

1, 1, 2, 4, 8, 16, 32, 65, 138, 316, 792, 2142, 6052, 17316, 49160, 137109, 374650, 1004848, 2658192, 6982424, 18351272, 48607148, 130447416, 355542916, 983250704, 2749502132, 7738681064, 21826783844, 61484999000, 172649101544

Offset

1,3

Links

Table of n, a(n) for n=1..30.

Index entries for reversions of series

Formula

Recurrence: 23*(n-2)*(n-1)*n*(2452*n^4 - 34960*n^3 + 189323*n^2 - 462197*n + 428952)*a(n) = 6*(n-2)*(n-1)*(68656*n^5 - 1081864*n^4 + 6762924*n^3 - 20914012*n^2 + 31827523*n - 18878553)*a(n-1) - 12*(n-2)*(88272*n^6 - 1611648*n^5 + 12190896*n^4 - 48980992*n^3 + 110413409*n^2 - 132553882*n + 66249909)*a(n-2) + 16*(63752*n^7 - 1387100*n^6 + 12908594*n^5 - 66715481*n^4 + 207163859*n^3 - 387112415*n^2 + 403580697*n - 181214694)*a(n-3) - 16*(n-4)*(n-2)*(19616*n^5 - 338528*n^4 + 2307676*n^3 - 7753912*n^2 + 12781431*n - 8182557)*a(n-4) + 128*(n-5)*(n-4)*(2*n - 11)*(2452*n^4 - 25152*n^3 + 99155*n^2 - 178623*n + 123570)*a(n-5). - Vaclav Kotesovec, Jan 02 2021

Mathematica

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

Crossrefs

Sequence in context: A325917 A210542 A141366 * A367661 A303023 A370340

Adjacent sequences: A049139 A049140 A049141 * A049143 A049144 A049145

Keyword

nonn

Author

Olivier Gérard

Status

approved