A099211 a(n) = -2*a(n-1) + 4*a(n-3), with a(0) = 1, a(1) = -2, a(2) = 4.

1, -2, 4, -4, 0, 16, -48, 96, -128, 64, 256, -1024, 2304, -3584, 3072, 3072, -20480, 53248, -94208, 106496, 0, -376832, 1179648, -2359296, 3211264, -1703936, -6029312, 24903680, -56623104, 89128960, -78643200, -69206016, 494927872, -1304428544, 2332033024, -2684354560

Offset: 0

Author

Paul Barry, Oct 06 2004

Keywords

• easy
• sign

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..1000
• Index entries for linear recurrences with constant coefficients, signature (-2,0,4).

Crossrefs

Cf. A099212.

Formula

G.f.: 1/(1 + 2*x - 4*x^3).

a(n) = A099212(n+4)/4.

Extensions

a(32) onwards from Andrew Howroyd, Mar 19 2025