OFFSET
0,1
REFERENCES
R. C. Alperin, A nonlinear recurrence and its relations to Chebyshev polynomials, Fib. Q., Vol. 58, No. 2 (2020), pp. 140-142.
LINKS
FORMULA
a(n) = a(n-1) + 3*(3n+1) = a(n-1) + A017197(n+1).
G.f.: (-2 - 8*x + x^2)/(x-1)^3. - R. J. Mathar, Jan 06 2011
a(n) = A144449(n)/8.
a(n) = 2*a(n-1) - a(n-2) + 9.
a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3).
From Amiram Eldar, Mar 11 2022: (Start)
Sum_{n>=0} 1/a(n) = 2/3.
Sum_{n>=0} (-1)^n/a(n) = 4*Pi/(9*sqrt(3)) + 4*log(2)/9 - 2/3. (End)
MAPLE
MATHEMATICA
Table[(1+3n)(4+3n)/2, {n, 0, 50}] (* Harvey P. Dale, Feb 23 2011 *)
PROG
(PARI) a(n)=(1+3*n)*(4+3*n)/2 \\ Charles R Greathouse IV, Jun 17 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, Oct 24 2008
EXTENSIONS
Terms a(11)-a(42) from Vincenzo Librandi, Nov 17 2009
STATUS
approved