OFFSET
0,2
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 0..10000
Index entries for linear recurrences with constant coefficients, signature (0,0,0,2,0,0,0,-1).
FORMULA
a(n) = 4n/gcd(n, 4).
a(n) = A084351(n), n > 1. - R. J. Mathar, Aug 20 2008
From R. J. Mathar, Apr 18 2011: (Start)
G.f.: 4*x*(1+x+3*x^2+x^3+3*x^4+x^5+x^6) / ( (x-1)^2*(1+x)^2*(x^2+1)^2 ).
Sum_{k=1..n} a(k) ~ (11/8) * n^2. - Amiram Eldar, Nov 26 2022
MATHEMATICA
Table[LCM[n, 4], {n, 0, 80}] (* Harvey P. Dale, May 02 2011 *)
PROG
(Magma) [Lcm(n, 4): n in [0..100]]; // Vincenzo Librandi, Apr 18 2011
(Haskell)
a109045 = lcm 4 -- Reinhard Zumkeller, Nov 25 2013
(PARI) a(n) = lcm(n, 4); \\ Michel Marcus, Mar 07 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mitch Harris, Jun 18 2005
STATUS
approved