|
|
|
|
4, 7, 19, 28, 64, 91, 199, 280, 604, 847, 1819, 2548, 5464, 7651, 16399, 22960, 49204, 68887, 147619, 206668, 442864, 620011, 1328599, 1860040, 3985804, 5580127, 11957419, 16740388, 35872264, 50221171, 107616799, 150663520, 322850404
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
FORMULA
|
a(n) = 3*a(n-2)+7 for n > 2; a(1) = 4, a(2) = 7.
a(n) = (11-4*(-1)^n)*3^(1/4*(2*n-1+(-1)^n))/2-7/2.
G.f.: x*(4+3*x)/((1-x)*(1-3*x^2)).
|
|
MATHEMATICA
|
LinearRecurrence[{1, 3, -3}, {4, 7, 19}, 40] (* Harvey P. Dale, Aug 28 2016 *)
|
|
PROG
|
(Magma) T:=[ n le 2 select 5-n else 3*Self(n-2): n in [1..33] ]; [ n eq 1 select T[1] else Self(n-1)+T[n]: n in [1..#T]];
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy,changed
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|