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

0,2

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).

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)

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 *)

Prog

(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

Crossrefs

Cf. A138377.

Sequence in context: A275762 A350626 A139248 * A016013 A193384 A325844

Adjacent sequences: A138377 A138378 A138379 * A138381 A138382 A138383

Keyword

sign,easy

Author

Paul Curtz, May 08 2008

Extensions

More terms from Harvey P. Dale, Mar 19 2012

Missing terms added by Colin Barker, Dec 01 2015

Status

approved