A137717 Hankel transform of A106191.

1, -4, 4, 8, -32, 32, 64, -256, 256, 512, -2048, 2048, 4096, -16384, 16384, 32768, -131072, 131072, 262144, -1048576, 1048576, 2097152, -8388608, 8388608, 16777216, -67108864, 67108864, 134217728, -536870912, 536870912

Offset

0,2

Comments

Hankel transform of A132310. - Paul Barry, Apr 26 2009

Links

Table of n, a(n) for n=0..29.

Index entries for linear recurrences with constant coefficients, signature (-2,-4).

Formula

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

a(n)=Product{k=0..n, (3*cos(2*pi*(k-1)/3)/2-5/4-2*0^k)^(n-k)};

a(n) = 2^n*A061347(n+2) = -2a(n-1)-4a(n-2). - R. J. Mathar, Feb 21 2008

Mathematica

LinearRecurrence[{-2, -4}, {1, -4}, 30] (* Harvey P. Dale, Oct 05 2017 *)

Prog

(PARI) a(n)=([0, 1; -4, -2]^n*[1; -4])[1, 1] \\ Charles R Greathouse IV, May 27 2026

Crossrefs

Apart from signs, essentially the same as A096252.

Cf. A106191, A061347, A132310.

Sequence in context: A264172 A019122 A019202 * A096252 A102369 A298569

Adjacent sequences: A137714 A137715 A137716 * A137718 A137719 A137720

Keyword

sign,easy

Author

Paul Barry, Feb 08 2008

Status

approved