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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A134751 Hankel transform of expansion of (1/(1-x^2))c(x/(1-x^2)), where c(x) is the g.f. of A000108. 5
1, 2, 8, 32, 256, 4096, 65536, 2097152, 134217728, 8589934592, 1099511627776, 281474976710656, 72057594037927936, 36893488147419103232, 37778931862957161709568, 38685626227668133590597632 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Hankel transform of A105864.

The sequence 1,1,2,8,... with general term 2^floor(n^2/3) is the Hankel transform of A109033. [From Paul Barry, Dec 14 2008]

a(n)=4*e(n-1)*e(n-3)/e(n-4). Somos-4 sequence associated to e.g. y^2=1-8x+16x^2-8x^3. [From Paul Barry, Nov 27 2009]

LINKS

Table of n, a(n) for n=0..15.

FORMULA

a(n)=2^floor((n+1)^2/3); a(n)=Product{k=1..n, (5/3-2*cos(2*pi*k/3)/3)^(n-k+1)}; a(n)=Product{k=1..n, A130196(k)^(n-k+1)};

CROSSREFS

Sequence in context: A048855 A262480 A062797 * A139014 A063505 A085466

Adjacent sequences:  A134748 A134749 A134750 * A134752 A134753 A134754

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Nov 08 2007

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 October 18 10:59 EDT 2019. Contains 328147 sequences. (Running on oeis4.)