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A109045
a(n) = lcm(n,4).
3
0, 4, 4, 12, 4, 20, 12, 28, 8, 36, 20, 44, 12, 52, 28, 60, 16, 68, 36, 76, 20, 84, 44, 92, 24, 100, 52, 108, 28, 116, 60, 124, 32, 132, 68, 140, 36, 148, 76, 156, 40, 164, 84, 172, 44, 180, 92, 188, 48, 196, 100, 204, 52, 212, 108, 220, 56, 228, 116, 236, 60
OFFSET
0,2
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 ).
a(n) = 4*n/A109008(n) = 4*A060819(n). (End)
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