login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A363092 a(n) = 4*a(n-1) - 8*a(n-2) with a(0) = a(1) = 1. 0
1, 1, -4, -24, -64, -64, 256, 1536, 4096, 4096, -16384, -98304, -262144, -262144, 1048576, 6291456, 16777216, 16777216, -67108864, -402653184, -1073741824, -1073741824, 4294967296, 25769803776, 68719476736, 68719476736, -274877906944, -1649267441664, -4398046511104 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
REFERENCES
Paul J. Nahin, An Imaginary Tale: The Story of sqrt(-1), Princeton University Press, Princeton, NJ. 1998, pp. 94-96.
LINKS
FORMULA
a(n) = 2^(3*n/2-1)*(2*cos(n*Pi/4) - sin(n*Pi/4)).
O.g.f.: (1 - 3*x)/(1 - 4*x + 8*x^2).
E.g.f.: exp(2*x)*(2*cos(2*x) - sin(2*x))/2.
a(n+1) = a(n) iff n is a multiple of 4.
MATHEMATICA
LinearRecurrence[{4, -8}, {1, 1}, 29]
CROSSREFS
Sequence in context: A166870 A124350 A112611 * A212066 A336039 A364600
KEYWORD
sign,easy
AUTHOR
Stefano Spezia, May 19 2023
STATUS
approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 22 22:43 EST 2024. Contains 370265 sequences. (Running on oeis4.)