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Search: id:A158851
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| A158851 |
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a(n) = LCM(1,2,3,...,n) (mod(n+1)). |
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+0
1
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| 1, 2, 2, 2, 0, 4, 4, 3, 0, 1, 0, 4, 0, 0, 8, 5, 0, 14, 0, 0, 0, 15, 0, 5, 0, 18, 0, 1, 0, 20, 16, 0, 0, 0, 0, 2, 0, 0, 0, 15, 0, 15, 0, 0, 0, 8, 0, 21, 0, 0, 0, 29, 0, 0, 0, 0, 0, 21, 0, 16, 0, 0, 32, 0, 0, 29, 0, 0, 0, 23, 0, 22, 0, 0, 0, 0, 0, 30, 0, 54, 0, 71, 0, 0, 0, 0, 0, 37, 0, 0, 0, 0, 0, 0, 0, 7, 0
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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If n+1 is not a power of a prime, then a(n) = 0.
If n+1 = p^m, p = prime, then p^(m-1) (= (n+1)/p) divides a(n), but p^m (= n+1) does not divide a(n).
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EXAMPLE
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LCM(1,2,3,4,5,6) = 60, which is congruent to 4 (mod 7). So a(6) = 4.
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MAPLE
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a := proc (n) options operator, arrow: `mod`(lcm(seq(j, j = 1 .. n)), n+1) end proc: seq(a(n), n = 1 .. 100); [From Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 03 2009]
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CROSSREFS
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A003418
Sequence in context: A000091 A155123 A125938 this_sequence A151930 A084203 A073358
Adjacent sequences: A158848 A158849 A158850 this_sequence A158852 A158853 A158854
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (q1qq2qqq3qqqq(AT)yahoo.com), Mar 28 2009
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 03 2009
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