login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A171408 a(n) = A171373(n+1) - 2*A171373(n). 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

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

Table of n, a(n) for n=0..41.

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

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).

CROSSREFS

Cf. A138112, A105371.

Sequence in context: A268368 A274947 A279406 * A071907 A172369 A190338

Adjacent sequences:  A171405 A171406 A171407 * A171409 A171410 A171411

KEYWORD

sign

AUTHOR

Paul Curtz, Dec 08 2009

EXTENSIONS

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

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 16 10:36 EDT 2019. Contains 327094 sequences. (Running on oeis4.)