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!)
A216206 a(n) = product_{i=1..n} ((-2)^i-1). 2
1, -3, -9, 81, 1215, -40095, -2525985, 325852065, 83092276575, -42626337882975, -43606743654283425, 89350217747626737825, 365889141676531491393375, -2997729737755822508985921375, -49111806293653640164716349886625, 1609344780436736134557590069434814625 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
Signed partial products of A062510. This implies that all terms from a(1) on are multiples of 3.
LINKS
FORMULA
A015109(n,k) = a(n)/(a(k)*a(n-k)).
a(n) = (-3)^n*A015013(n) for n>0, a(0)=1. [Bruno Berselli and Alonso del Arte, Mar 13 2013]
MAPLE
A216206 := proc(n)
mul( (-2)^i-1, i=1..n) ;
end proc:
MATHEMATICA
Table[(-1)^n QPochhammer[-2, -2, n], {n, 0, 15}] (* Bruno Berselli, Mar 13 2013 *)
CROSSREFS
Sequence in context: A121858 A215114 A032108 * A038062 A218149 A011764
KEYWORD
sign,easy
AUTHOR
R. J. Mathar, Mar 12 2013
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 26 04:47 EST 2024. Contains 370335 sequences. (Running on oeis4.)