OFFSET
1,1
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
G.f.: 64*x/(1-x)^4.
a(n) = 32*n*(n+1)*(n+2)/3 = 64*A000292(n).
a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4). - Vincenzo Librandi, Jun 29 2012
From Amiram Eldar, Aug 29 2022: (Start)
Sum_{n>=1} 1/a(n) = 3/128.
Sum_{n>=1} (-1)^(n+1)/a(n) = 3*log(2)/16 - 15/128. (End)
MAPLE
seq(binomial(n+2, 3)*4^3, n=1..36);
MATHEMATICA
CoefficientList[Series[64/(1-x)^4, {x, 0, 40}], x] (* Vincenzo Librandi, Jun 29 2012 *)
PROG
(Magma) [Binomial(n+2, 3)*4^3: n in [1..34]]; // Bruno Berselli, Apr 07 2011
(Magma) I:=[64, 256, 640, 1280]; [n le 4 select I[n] else 4*Self(n-1)-6*Self(n-2)+4*Self(n-3)-Self(n-4): n in [1..50]]; // Vincenzo Librandi, Jun 29 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Zerinvary Lajos, Aug 09 2008
EXTENSIONS
Offset adapted to the g.f. by Bruno Berselli, Apr 07 2011
STATUS
approved