|
|
A001585
|
|
a(n) = 3^n + n^3.
|
|
12
|
|
|
1, 4, 17, 54, 145, 368, 945, 2530, 7073, 20412, 60049, 178478, 533169, 1596520, 4785713, 14352282, 43050817, 129145076, 387426321, 1162268326, 3486792401, 10460362464, 31381070257, 94143190994, 282429550305, 847288625068
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
COMMENTS
|
In this sequence if we do a forward difference, then the 4th forward difference when considered as a sequence will be a geometric progression with common ratio 3. - Gopalakrishnan (gopala498(AT)yahoo.co.in), May 26 2010
|
|
LINKS
|
|
|
FORMULA
|
G.f.: (-1+2*x^4+15*x^3-7*x^2+3*x)/((3*x-1)*(x-1)^4). - Maksym Voznyy (voznyy(AT)mail.ru), Jul 27 2009
|
|
MAPLE
|
|
|
MATHEMATICA
|
|
|
PROG
|
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|