OFFSET
1,1
LINKS
Index entries for linear recurrences with constant coefficients, signature (2,-2,2,-1).
FORMULA
a(n) = 2a(n-1) - 2a(n-2) + 2a(n-3) - a(n-4). - Charles R Greathouse IV, Nov 09 2012
G.f.: x^2*(x^3+4*x^2-x+2) / ((x-1)^2*(x^2+1)). - Colin Barker, Jan 07 2013
{m>1|C(m,4)==0 (mod C(m,2))}. - Gary Detlefs, Jan 11 2014
Sum_{n>=1} (-1)^(n+1)/a(n) = (2*sqrt(3)+1)*Pi/24 - log(2+sqrt(3))/(4*sqrt(3)) - log(2)/6. - Amiram Eldar, Mar 18 2022
MATHEMATICA
LinearRecurrence[{2, -2, 2, -1}, {2, 3, 6, 11}, 100] (* T. D. Noe, Nov 11 2012 *)
PROG
(PARI) for(m=2, 175, if(binomial(m, 4)%binomial(m, 2)==0, print1(m, ", "))) \\ Hugo Pfoertner, Aug 11 2020
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jean-Claude Babois, Oct 22 2012
EXTENSIONS
Edited by Andrey Zabolotskiy, Aug 11 2020
STATUS
approved