A152174 a(n) = -2*a(n-1)+4*a(n-2), n>1 ; a(0) = 1, a(1) = -4.

1, -4, 12, -40, 128, -416, 1344, -4352, 14080, -45568, 147456, -477184, 1544192, -4997120, 16171008, -52330496, 169345024, -548012032, 1773404160, -5738856448, 18571329536, -60098084864, 194481487872, -629355315200

Offset: 0

Author

Philippe Deléham, Nov 27 2008

Keywords

• sign
• easy

Comments

Signed version of A087206.

Links

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

Crossrefs

Cf. A087206, A147703.

Programs

Mathematica

LinearRecurrence[{-2,4},{1,-4},30] (* Harvey P. Dale, Feb 13 2023 *)

PARI

Vec((1-2*x)/(1+2*x-4*x^2)+O(x^99)) \\ Charles R Greathouse IV, Jan 11 2012

Formula

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

a(n) = Sum_{k=0..n} A147703(n,k)*(-5)^k.

a(n) = (-1)^n * A087206(n).