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A130317
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Smallest number having exactly n triangular divisors.
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10
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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
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OFFSET
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1,2
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COMMENTS
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2*a(n) is smallest number having exactly n oblong divisors.
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LINKS
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FORMULA
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EXAMPLE
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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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PROG
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(PARI) a(n) = my(k=1); while (sumdiv(k, d, ispolygonal(d, 3)) != n, k++); k; \\ Michel Marcus, Jan 14 2022
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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