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Search: id:A130799
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| A130799 |
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Triangle read by rows in which row n (n>=3) list the anti-divisors of n. |
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+0
6
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| 2, 3, 2, 3, 4, 2, 3, 5, 3, 5, 2, 6, 3, 4, 7, 2, 3, 7, 5, 8, 2, 3, 5, 9, 3, 4, 9, 2, 6, 10, 3, 11, 2, 3, 5, 7, 11, 4, 5, 7, 12, 2, 3, 13, 3, 8, 13, 2, 6, 14, 3, 4, 5, 9, 15, 2, 3, 5, 9, 15, 7, 16, 2, 3, 7, 10, 17, 3, 4, 17, 2, 5, 6, 11, 18, 3, 5, 8, 11, 19, 2, 3, 19, 4, 12, 20, 2, 3, 7
(list; graph; listen)
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OFFSET
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3,1
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COMMENT
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A066272 gives the number of terms in each row.
See A066272 for definition of anti-divisor.
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LINKS
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T. D. Noe, Rows n=3..1000 of triangle, flattened
Diana Mecum, Rows 3 through 500
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EXAMPLE
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Anti-divisors of 3 through 20:
3: 2
4: 3
5: 2, 3
6: 4
7: 2, 3, 5
8: 3, 5
9: 2, 6
10: 3, 4, 7
11: 2, 3, 7
12: 5, 8
13: 2, 3, 5, 9
14: 3, 4, 9
15: 2, 6, 10
16: 3, 11
17: 2, 3, 5, 7, 11
18: 4, 5, 7, 12
19: 2, 3, 13
20: 3, 8, 13
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MATHEMATICA
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f[n_] := Complement[ Sort@ Join[ Select[ Union@ Flatten@ Divisors[{2 n - 1, 2 n + 1}], OddQ@ # && # < n &], Select[ Divisors[2 n], EvenQ@ # && # < n &]], Divisors@ n]; Flatten@ Table[ f@n, {n, 3, 32}] (* Robert G. Wilson v (rgwv@rgwv.com), Jul 17 2007 *)
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CROSSREFS
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Sequence in context: A003051 A097352 A076050 this_sequence A106383 A105500 A088748
Adjacent sequences: A130796 A130797 A130798 this_sequence A130800 A130801 A130802
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KEYWORD
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nonn
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AUTHOR
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Diana Mecum (diana.mecum(AT)gmail.com), Jul 17 2007
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