OFFSET
0,2
LINKS
Ivan Panchenko, Table of n, a(n) for n = 0..200
Eric Weisstein's World of Mathematics, Polygamma Function.
Wikipedia, Polygamma Function.
Index entries for linear recurrences with constant coefficients, signature (3,-3,1).
FORMULA
a(n) = 3*a(n-1) -3*a(n-2) +a(n-3). - Harvey P. Dale, Jul 11 2012
Sum_{n>=0} 1/a(n) = polygamma(1, 1/5)/25 = 1.050695088216... - Amiram Eldar, Oct 02 2020
G.f.: (1 +33*x +16*x^2)/(1-x)^3. - Wesley Ivan Hurt, Oct 02 2020
From G. C. Greubel, Dec 28 2022: (Start)
a(2*n) = A017282(n).
a(2*n+1) = 4*A016886(n).
E.g.f.: (1 + 35*x + 25*x^2)*exp(x). (End)
MATHEMATICA
(5*Range[0, 40]+1)^2 (* or *) LinearRecurrence[{3, -3, 1}, {1, 36, 121}, 40] (* Harvey P. Dale, Jul 11 2012 *)
PROG
(PARI) a(n)=(5*n+1)^2 \\ Charles R Greathouse IV, Jun 17 2017
(Magma) [(5*n+1)^2: n in [0..40]]; // G. C. Greubel, Dec 28 2022
(SageMath) [(5*n+1)^2 for n in range(41)] # G. C. Greubel, Dec 28 2022
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved