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A130317
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Smallest number having exactly n triangular divisors.
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3
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1, 3, 6, 36, 30, 90, 180, 210, 420, 630, 1890, 1260, 2520, 6930, 18480, 20790, 13860, 27720, 41580, 83160, 138600, 245700, 235620, 180180, 556920, 360360, 540540, 1670760, 1081080, 1413720, 2702700, 2162160, 6486480, 3063060, 8288280
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| 2*a(n) is smallest number having exactly n oblong divisors.
A007862(a(n)) = n and A007862(m) <> n for m < a(n).
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LINKS
| Ray Chandler, Table of n, a(n) for n=1..58
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FORMULA
| a(n) = A088726(n-1)/2 for n>1. - Chandler
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EXAMPLE
| a(3)=6: A007862(6)=#{1,2*(2+1)/2,3*(3+1)/2}=3;
a(4)=36: A007862(36)=#{1,2*(2+1)/2,3*(3+1)/2,8*(8+1)/2}=4;
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CROSSREFS
| Cf. A130279.
Sequence in context: A009197 A205336 A184390 * A019467 A119186 A119115
Adjacent sequences: A130314 A130315 A130316 * A130318 A130319 A130320
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KEYWORD
| nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 23 2007
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EXTENSIONS
| Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jun 24 2008
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