OFFSET
0,2
COMMENTS
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).
FORMULA
G.f.: (1+31x-50x^2+35x^3-9x^4)/(1-x)^4.
a(n) = (2*n+5)*(2*n+3)*(n+2)/3, n>0. - R. J. Mathar, Oct 13 2011
MATHEMATICA
CoefficientList[Series[(1+31x-50x^2+35x^3-9x^4)/(1-x)^4, {x, 0, 40}], x] (* Vincenzo Librandi, Jun 30 2012 *)
LinearRecurrence[{4, -6, 4, -1}, {1, 35, 84, 165, 286}, 40] (* Harvey P. Dale, Mar 25 2022 *)
PROG
(Magma) I:=[1, 35, 84, 165, 286]; [n le 5 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 30 2012
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Feb 04 2009
STATUS
approved