|
| |
|
|
A135032
|
|
a(n) = 6*a(n-1) + 4*a(n-2).
|
|
4
| |
|
|
0, 1, 6, 40, 264, 1744, 11520, 76096, 502656, 3320320, 21932544, 144876544, 956989440, 6321442816, 41756614656, 275825459200, 1821979213824, 12035177119744, 79498979573760, 525134585921536, 3468803433824256
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 0,3
|
|
|
COMMENTS
| For n>=2, a(n) equals the permanent of the (n-1)X(n-1) tridiagonal matrix with 6's along the main diagonal, and 2's along the superdiagonal and the subdiagonal. [From John M. Campbell, Jul 19 2011]
|
|
|
FORMULA
| a(0)=0; a(1)=1; a(n)=2*(3*a(n-1)+2*a(n-2)).
a(n)=1/(2*sqrt(13))*((3+sqrt(13))^n-(3-sqrt(13))^n).
|
|
|
MATHEMATICA
| Join[{a=0, b=1}, Table[c=6*b+4*a; a=b; b=c, {n, 100}]] (*From Vladimir Joseph Stephan Orlovsky, Jan 16 2011*)
|
|
|
PROG
| (Sage) [lucas_number1(n, 6, -4) for n in xrange(0, 21)] # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Apr 24 2009]
|
|
|
CROSSREFS
| Sequence in context: A026077 A065113 A052518 * A122074 A123357 A081016
Adjacent sequences: A135029 A135030 A135031 * A135033 A135034 A135035
|
|
|
KEYWORD
| nonn,easy
|
|
|
AUTHOR
| Rolf Pleisch (r_pleisch(AT)gmx.ch), Feb 10 2008, corrected Feb 14 2008
|
|
|
EXTENSIONS
| More terms from Alexis Olson (AlexisOlson(AT)gmail.com), Nov 15 2008
|
| |
|
|
