OFFSET
1,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..10000
Index entries for linear recurrences with constant coefficients, signature (4,-6,4,-1).
FORMULA
a(n) = n*(6*n^2 - 3*n - 1)/2.
G.f.: x*(1 + 13*x + 4*x^2) / (x-1)^4. - R. J. Mathar, Oct 08 2011
2*a(n) = A213826(n). - Clark Kimberling, Jul 04 2012
E.g.f.: (1/2)*(2*x + 15*x^2 + 6*x^3)*exp(x). - Franck Maminirina Ramaharo, Nov 23 2018
MATHEMATICA
a[n_] := n*(6*n^2 - 3*n - 1)/2; Array[a, 50] (* Amiram Eldar, Nov 23 2018 *)
Accumulate[Range[1, 202, 3]^2] (* Harvey P. Dale, Aug 24 2019 *)
PROG
(Magma) [n*(6*n^2-3*n-1)/2: n in [1..40]]; // Vincenzo Librandi, Oct 10 2011
(PARI) a(n)=n*(6*n^2-3*n-1)/2 \\ Charles R Greathouse IV, Oct 07 2015
(Sage) [n*(6*n^2-3*n-1)/2 for n in (1..40)] # G. C. Greubel, Nov 23 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved