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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A133592 a(n)=2*a(n-1)+6*a(n-2) for n>=3, a(0)=1, a(1)=2, a(2)=8 . 2
1, 2, 8, 28, 104, 376, 1376, 5008, 18272, 66592, 242816, 885184, 3227264, 11765632, 42894848, 156383488, 570136064, 2078573056, 7577962496, 27627363328, 100722501632, 367209183232, 1338753376256, 4880761851904, 17794043961344 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..24.

Index entries for linear recurrences with constant coefficients, signature (2,6).

FORMULA

G.f.: (1-2*x^2)/(1-2*x-6*x^2) . a(n) = Sum_{k, 0<=k<=n}A122950(n,k)*2^k .

a(n)=[1+sqrt(7)]^(n-1)+[1-sqrt(7)]^(n-1)-(3/7)*[1-sqrt(7)]^(n-1)*sqrt(7)+(3/7)*[1+sqrt(7)]^(n-1)*sqrt(7) +(1/3)*[C(2*n,n) mod 2], with n>=0 [From Paolo P. Lava, Nov 18 2008]

((7+2*sqrt(7))/21)*(1+sqrt(7))^n+((7-2*sqrt(7))/21)*(1-sqrt(7))^n for n=>1 [From Richard Choulet, Nov 19 2008]

a(n) = A083099(n+1) - 2*A083099(n-1). - R. J. Mathar, Jun 20 2015

MAPLE

A133592 := proc(n)

        option remember;

        if n <=1 then

                n+1;

        elif n = 2 then

                8;

        else

                2*procname(n-1)+6*procname(n-2) ;

        fi ;

end proc: # R. J. Mathar, Jul 15 2017

CROSSREFS

Sequence in context: A104934 A056711 A114590 * A115967 A150714 A292668

Adjacent sequences:  A133589 A133590 A133591 * A133593 A133594 A133595

KEYWORD

easy,nonn

AUTHOR

Philippe Deléham, Dec 31 2007

EXTENSIONS

a(16) corrected by R. J. Mathar, Jun 20 2015

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 December 15 22:02 EST 2019. Contains 330012 sequences. (Running on oeis4.)