A138380 First differences of A138377.

1, 2, -1, -2, -4, -8, 4, 8, 16, 32, -16, -32, -64, -128, 64, 128, 256, 512, -256, -512, -1024, -2048, 1024, 2048, 4096, 8192, -4096, -8192, -16384, -32768, 16384, 32768, 65536, 131072, -65536, -131072, -262144, -524288, 262144, 524288, 1048576, 2097152

Offset: 0

Author

Paul Curtz, May 08 2008

Keywords

• sign
• easy

Comments

All terms are powers of 2 (see comment in A138377). - Michel Marcus, Dec 01 2015

Links

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

Crossrefs

Cf. A138377.

Programs

Mathematica

Differences[LinearRecurrence[{0,0,0,-4},{0,1,3,2},60]] (* Harvey P. Dale, Mar 19 2012 *)
LinearRecurrence[{0, 0, 0, -4},{1, 2, -1, -2},59] (* Ray Chandler, Aug 03 2015 *)

PARI

Vec((1-x)*(1+x)*(1+2*x)/((1-2*x+2*x^2)*(1+2*x+2*x^2)) + O(x^100)) \\ Colin Barker, Dec 01 2015

Formula

From Colin Barker, Dec 01 2015: (Start)

a(n) = -4*a(n-4) for n>3.

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

(End)

Extensions

More terms from Harvey P. Dale, Mar 19 2012

Missing terms added by Colin Barker, Dec 01 2015