A171408 a(n) = A171373(n+1) - 2*A171373(n).

4, 4, 4, 4, 0, -12, -32, -52, -52, 0, 136, 356, 576, 576, 0, -1508, -3948, -6388, -6388, 0, 16724, 43784, 70844, 70844, 0, -185472, -485572, -785672, -785672, 0, 2056916, 5385076, 8713236, 8713236, 0, -22811548, -59721408, -96631268, -96631268, 0, 252983944, 662320564

Offset: 0

Author

Paul Curtz, Dec 08 2009

Keywords

• sign

Comments

The least significant digits have a period of length 20. Another period (not the same but of the same length, as this a sequence contains negative numbers) is defined reading the sequence modulo 10.

Links

• Index entries for linear recurrences with constant coefficients, signature (3,-4,2,-1)

Crossrefs

Cf. A138112, A105371.

Formula

a(n)=4*A105371(n-1), n>0.

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

Extensions

Edited and extended by R. J. Mathar, Mar 02 2010