|
|
A003674
|
|
2^(n-1)*( 2^n - (-1)^n ).
|
|
1
|
|
|
0, 3, 6, 36, 120, 528, 2016, 8256, 32640, 131328, 523776, 2098176, 8386560, 33558528, 134209536, 536887296, 2147450880, 8590000128, 34359607296, 137439215616, 549755289600, 2199024304128, 8796090925056
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
COMMENTS
|
Given the 2x2 matrix M = [1,3; 3,1], a(n) = term (1,2) in M^n, n>0. [From Gary W. Adamson, Aug 06 2010]
|
|
REFERENCES
|
M. Gardner, Riddles of the Sphinx, New Mathematical Library, M.A.A., 1987, p. 145. Math. Rev. 89i:00015.
|
|
LINKS
|
Table of n, a(n) for n=0..22.
|
|
FORMULA
|
G.f.: 3x/((1+2x)(1-4x)).
|
|
PROG
|
(PARI) a(n)=if(n<0, 0, 2^(n-1)*(2^n-(-1)^n))
|
|
CROSSREFS
|
Sequence in context: A084260 A076983 A068084 * A211895 A240986 A120595
Adjacent sequences: A003671 A003672 A003673 * A003675 A003676 A003677
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
N. J. A. Sloane.
|
|
STATUS
|
approved
|
|
|
|