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Search: id:A130874
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| A130874 |
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Anti-divisorial numbers: the product of all anti-divisors of all integers equal or less than n. |
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+0
2
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| 2, 6, 36, 144, 4320, 64800, 777600, 65318400, 2743372800
(list; graph; listen)
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OFFSET
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3,1
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COMMENT
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Different from the anti-primorial, which is the partial products of anti-primes.
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FORMULA
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a(n) = PRODUCT[k=3..n] {anti-divisors(k)} = PRODUCT[k=3..n] PRODUCT[j=1..A066272(k)] (j-th element of k-th row of A130799) = partial products of A091507.
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EXAMPLE
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a(11) = anti-divisors of 3 * anti-divisors of 4 * ... * anti-divisors of 11 = (2) * (3) * (2 * 3) * (4) * (2 * 3 * 5) * (3 * 5) * (2 * 6) * (3 * 4 * 7) * (2 * 3 * 7) = 2743372800.
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CROSSREFS
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Cf. A066272, A091507, A130799.
Sequence in context: A034526 A120824 A127564 this_sequence A019020 A101609 A086325
Adjacent sequences: A130871 A130872 A130873 this_sequence A130875 A130876 A130877
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost2(AT)yahoo.com), Jul 25 2007
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