OFFSET
0,2
COMMENTS
All terms are multiples of 3.
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..5000
Index entries for linear recurrences with constant coefficients, signature (0,0,0,3,0,0,0,-3,0,0,0,1).
FORMULA
a(n) = A142600(n-1), n>1.
G.f.: -3*x*(7*x^10 +5*x^9 +39*x^8 +4*x^7 +74*x^6 +18*x^5 +58*x^4 +2*x^3 +15*x^2 +x -1) / ((x -1)^3*(x +1)^3*(x^2 +1)^3). - Colin Barker, Oct 15 2014
Sum_{n>=1} 1/a(n) = 11*log(3)/16 - 5*Pi/(48*sqrt(3)) - 1/4. - Amiram Eldar, Sep 11 2022
MATHEMATICA
Table[Numerator[(n-2)*(n+2)/(4*n^2)], {n, -2, 300, 3}] (* Vaclav Kotesovec, Oct 15 2014 *)
PROG
(PARI) concat(0, Vec(-3*x*(7*x^10 +5*x^9 +39*x^8 +4*x^7 +74*x^6 +18*x^5 +58*x^4 +2*x^3 +15*x^2 +x -1) / ((x -1)^3*(x +1)^3*(x^2 +1)^3) + O(x^100))) \\ Colin Barker, Oct 15 2014
(Magma) I:=[0, -3, 3, 45, 6, 165, 63, 357, 30, 621, 195, 957]; [n le 12 select I[n] else 3*Self(n-4)-3*Self(n-8)+Self(n-12): n in [1..50]]; // Vincenzo Librandi, Oct 15 2014
CROSSREFS
KEYWORD
sign,easy,frac,less
AUTHOR
Paul Curtz, Nov 27 2010
STATUS
approved