OFFSET
1,3
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
MATHEMATICA
nn=30; With[{fr=Accumulate[Table[1/(n (-1)^(n-1)), {n, nn}]]}, Table[fr[[n]] LCM@@ Range[n], {n, nn}]] (* Harvey P. Dale, Dec 27 2012 *)
PROG
(Haskell)
a025530 n = sum $ map (div (a003418 $ fromInteger n))
(zipWith (*) [1..n] a033999_list)
-- Reinhard Zumkeller, Dec 23 2011
(PARI) a(n)=my(v=primes(primepi(n)), k=sqrtint(n), L=log(n+.5), t); t=prod(i=1, #v, if(v[i]>k, v[i], v[i]^(L\log(v[i])))); -sum(i=1, n, (-1)^i*t/i) \\ Charles R Greathouse IV, Dec 23 2011
(PARI) s=1; v=vector(10^4, i, 1); for(n=2, #v, t=n/gcd(s, n); s*=t; v[n]=v[n-1]*t-(-1)^n*s/n); v \\ Charles R Greathouse IV, Dec 23 2011
CROSSREFS
KEYWORD
nonn,easy,nice
AUTHOR
STATUS
approved