|
|
A099359
|
|
a(n) = (2^n + 1)^3 - 2.
|
|
4
|
|
|
6, 25, 123, 727, 4911, 35935, 274623, 2146687, 16974591, 135005695, 1076890623, 8602523647, 68769820671, 549957165055, 4398851866623, 35187593412607, 281487861809151, 2251851353686015, 18014604668698623, 144116012711149567, 1152924803144876031
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,1
|
|
LINKS
|
|
|
FORMULA
|
a(n) = (3*2^n + 3*4^n + 8^n - 1).
a(n) = 15*a(n-1) - 70*a(n-2) + 120*a(n-3) - 64*a(n-4) for n>3.
G.f.: (6 - 65*x + 168*x^2 - 88*x^3) / ((1 - x)*(1 - 2*x)*(1 - 4*x)*(1 - 8*x)).
(End)
|
|
EXAMPLE
|
(2^1 + 1)^3 - 2 = 25.
|
|
MATHEMATICA
|
|
|
PROG
|
(PARI) Vec((6 - 65*x + 168*x^2 - 88*x^3) / ((1 - x)*(1 - 2*x)*(1 - 4*x)*(1 - 8*x)) + O(x^30)) \\ Colin Barker, Jan 10 2017
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|