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 A155724: a(n) = Sum_{m=1..n} (2*m*n + m + n - 4).
From Vincenzo Librandi, Mar 04 2012: (Start)
G.f.: x^2*(11 - 5*x)/(1-x)^4.
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4). (End)
a(n) = A151675(n) - 8*n. - L. Edson Jeffery, Oct 12 2012
From Amiram Eldar, Feb 25 2023: (Start)
Sum_{n>=2} 1/a(n) = 8*log(2)/63 + 1166/19845.
Sum_{n>=2} (-1)^n/a(n) = (32*log(2) - 2*Pi - 3566/315)/63. (End)
MATHEMATICA
CoefficientList[Series[x*(11-5*x)/(1-x)^4, {x, 0, 40}], x] (* or *) LinearRecurrence[{4, -6, 4, -1}, {0, 11, 39, 90}, 50](* Vincenzo Librandi, Mar 04 2012 *)
PROG
(Magma) [(2*n^3 + 5*n^2 - 7*n)/2 : n in [1..50]]; // Wesley Ivan Hurt, May 07 2021
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Jun 29 2009
EXTENSIONS
New name from Vincenzo Librandi, Mar 04 2012
STATUS
approved