OFFSET
1,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (4, -6, 4, -1).
FORMULA
Row sums from A155546: a(n) = Sum_{m=1..n} (2*m*n + m + n - 5).
From Vincenzo Librandi, Mar 04 2012: (Start)
G.f.: x*(-1 + 13*x - 6*x^2)/(1-x)^4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4). (End)
MATHEMATICA
LinearRecurrence[{4, -6, 4, -1}, {-1, 9, 36, 86}, 50] (* or *) CoefficientList[Series[(2+7*x-3*x^2)/(1-x)^4, {x, 0, 50}], x] (* Vincenzo Librandi, Mar 04 2012 *)
CROSSREFS
KEYWORD
sign,easy
AUTHOR
Vincenzo Librandi, Jun 29 2009
EXTENSIONS
New name from Vincenzo Librandi, Mar 04 2012
STATUS
approved