|
|
A162257
|
|
a(n) = (2*n^3 + 5*n^2 - 11*n)/2.
|
|
1
|
|
|
-2, 7, 33, 82, 160, 273, 427, 628, 882, 1195, 1573, 2022, 2548, 3157, 3855, 4648, 5542, 6543, 7657, 8890, 10248, 11737, 13363, 15132, 17050, 19123, 21357, 23758, 26332, 29085, 32023, 35152, 38478, 42007, 45745, 49698, 53872, 58273, 62907, 67780
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
FORMULA
|
Row sums from A155550: a(n) = Sum_{m=1..n} 2*m*n + m + n - 6.
G.f.: x*(-2 + 15*x - 7*x^2)/(1-x)^4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4). (End)
|
|
MAPLE
|
|
|
MATHEMATICA
|
CoefficientList[Series[(-2+15*x-7*x^2)/(1-x)^4, {x, 0, 40}], x] (* or *) LinearRecurrence[{4, -6, 4, -1}, {-2, 7, 33, 82}, 50] (* Vincenzo Librandi, Mar 04 2012 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
sign,easy
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|