OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..10000
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
G.f.: (1 + 61*x + 36*x^2)/(1-x)^3. - Vincenzo Librandi, Jan 27 2013
From G. C. Greubel, Dec 28 2022: (Start)
a(2*n) = A134934(n).
a(2*n+1) = 4*A017030(n).
E.g.f.: (1 + 63*x + 49*x^2)*exp(x). (End)
Sum_{n>=0} 1/a(n) = Psi'(1/7)/49 = 1.027703498712483534.. - R. J. Mathar, May 07 2024
MATHEMATICA
(7Range[0, 50]+1)^2 (* Harvey P. Dale, Mar 05 2011 *)
CoefficientList[Series[(1+61*x+36*x^2)/(1-x)^3, {x, 0, 40}], x] (* Vincenzo Librandi, Jan 27 2013 *)
PROG
(Magma) [(7*n+1)^2: n in [0..40]]; // Vincenzo Librandi, Jul 13 2011
(PARI) a(n)=(7*n+1)^2 \\ Charles R Greathouse IV, Jun 17 2017
(SageMath) [(7*n+1)^2 for n in range(41)] # G. C. Greubel, Dec 28 2022
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved