|
|
A114553
|
|
a(n) = 25*a(n-2) + 48*a(n-3) with a(0) = 0, a(1) = a(2) = 1.
|
|
1
|
|
|
0, 1, 1, 25, 73, 673, 3025, 20329, 107929, 653425, 3674017, 21516217, 123214825, 714258241, 4113149041, 23770767625, 137113121593, 791700344593, 4568824885825, 26373938451289, 152222238686089, 878652055801825
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,4
|
|
LINKS
|
|
|
FORMULA
|
a(n) = w(n)((1)) where w(n) = M*w(n-1), w(0) = {0, 1, 1}, and M = {{0, 1, 0}, {0, 0, 1}, {48, 25, 0}}.
a(n) = 25*a(n-2) + 48*a(n-3).
G.f.: x*(1+x)/((1+3*x)*(1-3*x-16*x^2)). (End)
a(n) = (4*i)^(n-1)*(4*i*ChebyshevU(n, -3*I/8) - 5*ChebyshevU(n-1, -3*I/8)) - (-3)^n. - G. C. Greubel, Jul 07 2021
|
|
MATHEMATICA
|
M = {{0, 1, 0}, {0, 0, 1}, {48, 25, 0}}; w[0] = {0, 1, 1};
w[n_]:= w[n]= M.w[n - 1];
Table[w[n][[1]], {n, 0, 30}]
LinearRecurrence[{0, 25, 48}, {0, 1, 1}, 30] (* Harvey P. Dale, Mar 26 2013 *)
|
|
PROG
|
(Magma) I:=[0, 1, 1]; [n le 3 select I[n] else 25*Self(n-2) + 48*Self(n-3): n in [1..31]]; // G. C. Greubel, Jul 07 2021
(Sage)
def a(n, q): return 0 if (n==0) else 1 if (n<3) else q^2*a(n-2, q) + 2*(q^2-1)*a(n-3, q)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|