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Search: id:A140813
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| A140813 |
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Smallest number divisible by all integers 1 through n as well as all composite numbers 1 through 2n. |
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+0
1
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| 4, 12, 24, 360, 360, 2520, 5040, 5040, 5040, 55440, 55440, 3603600, 10810800, 10810800, 21621600, 367567200, 367567200, 6983776800, 6983776800, 6983776800, 6983776800, 160626866400, 160626866400, 1124388064800, 1124388064800
(list; graph; listen)
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OFFSET
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2,1
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COMMENT
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Is this a subsequence of A002182?
Is this a subsequence of A002182? - That is not the case. a(79) = 10703173554082014360835514860858032000 is the smallest term that is not in A002182. [From Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Aug 28 2008]
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LINKS
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Klaus Brockhaus, Table of n, a(n) for n=2..200
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EXAMPLE
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a(5) is 360 because 360 is divisible by all numbers 1 through 5 (1, 2, 3, 4, 5) as well as all composite numbers up to 10 (4, 6, 8, 9, 10).
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PROGRAM
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(PARI) {m=26; a=1; for(n=2, m, print1(a=lcm([a, n, 2*n, if(isprime(k=2*n-1), n, k)]), ", "))} /* Klaus Brockhaus, Jul 24 2008 */
(MAGMA) m:=26; [ Lcm([ x: x in [1..n] ] cat [ x: x in [n+1..2*n] | not IsPrime(x) ]): n in [2..m] ]; /* Klaus Brockhaus, Jul 24 2008 */
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CROSSREFS
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Sequence in context: A025543 A064354 A073841 this_sequence A032339 A103471 A114979
Adjacent sequences: A140810 A140811 A140812 this_sequence A140814 A140815 A140816
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KEYWORD
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nonn
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AUTHOR
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J. Lowell (jhbubby(AT)mindspring.com), Jul 16 2008
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EXTENSIONS
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More terms from Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Jul 24 2008
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