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A025530
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(1/1 - 1/2 + ... + d/n)*LCM{1,2,...,n}, where d = (-1)^(n-1).
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4
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1, 1, 5, 7, 47, 37, 319, 533, 1879, 1627, 20417, 18107, 263111, 237371, 261395, 477745, 8842385, 8161705, 167324635, 155685007, 166770367, 156188887, 3825136961, 3602044091, 19081066231, 18051406831, 57128792093, 54260455193, 1653866633797
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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LINKS
| Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
Index entries for sequences related to lcm's
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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
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CROSSREFS
| Cf. A058312, A058313, A003418, A033999.
Sequence in context: A058313 A120301 A119787 * A106114 A110420 A123789
Adjacent sequences: A025527 A025528 A025529 * A025531 A025532 A025533
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KEYWORD
| nonn,easy,nice
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AUTHOR
| Clark Kimberling (ck6(AT)evansville.edu)
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