|
|
A060919
|
|
Number of corners in a 4-sided fractal.
|
|
6
|
|
|
4, 8, 20, 60, 204, 748, 2860, 11180, 44204, 175788, 701100, 2800300, 11193004, 44755628, 178989740, 715893420, 2863442604, 11453508268, 45813508780, 183252986540, 733009849004, 2932035201708, 11728132418220, 46912512895660
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
FORMULA
|
a(n) = 7*a(n-1)-14*a(n-2)+8*a(n-3). G.f.: -4*x*(5*x^2-5*x+1) / ((x-1)*(2*x-1)*(4*x-1)). [Colin Barker, Nov 28 2012]
|
|
MATHEMATICA
|
LinearRecurrence[{7, -14, 8}, {4, 8, 20}, 30] (* Harvey P. Dale, Sep 01 2023 *)
|
|
PROG
|
(PARI) { for (n=1, 200, write("b060919.txt", n, " ", (2^n + 2)*(2^n + 4)/6); ) } \\ Harry J. Smith, Jul 14 2009
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|