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Search: id:A025558
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| A025558 |
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((n-1)/n)*LCM{1,2,...,n}. |
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+0
5
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| 1, 4, 9, 48, 50, 360, 735, 2240, 2268, 25200, 25410, 332640, 334620, 336336, 675675, 11531520, 11571560, 220540320, 221152932, 221707200, 222211080, 5121436320, 5131136010, 25700298624, 25741485000, 77338861600, 77445096300, 2248776129600
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OFFSET
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1,2
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COMMENT
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a(n) = (1/1 + 1/3 + 1/6 + ... + 1/C(n+1,2))*lcm(1,3,6,...,binomial(n+1,2)) = 2n/(n+1) * lcm(1,3,6,...,binomial(n+1,2)).
a(n+1) = a(n) * ((n+1)^2)/(n * ((n+2)/p) ), where p = n+2 if n+2 is prime, p = q if n+2 = q^k (q is prime, k>1), or p = 1 if n+2 is not a prime or a prime power. - Scott C. Macfarlan (scottmacfarlan(AT)covance.com), Jan 08 2004
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CROSSREFS
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a(n) = n*A002944(n) = ((n-1)/n)*A003418(n).
Sequence in context: A024053 A048892 A108849 this_sequence A103933 A013495 A164839
Adjacent sequences: A025555 A025556 A025557 this_sequence A025559 A025560 A025561
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KEYWORD
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nonn
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AUTHOR
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Clark Kimberling (ck6(AT)evansville.edu)
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EXTENSIONS
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Entry revised by N. J. A. Sloane (njas(AT)research.att.com), Nov 12 2004
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