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A074285
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Sum of the divisors of n-th triangular number.
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18
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1, 4, 12, 18, 24, 32, 56, 91, 78, 72, 144, 168, 112, 192, 360, 270, 234, 260, 360, 576, 384, 288, 672, 868, 434, 560, 960, 720, 720, 768, 992, 1488, 864, 864, 1872, 1482, 760, 1120, 2352, 1764, 1344, 1408, 1584, 2808, 1872, 1152, 2880, 3420, 1767, 2232
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OFFSET
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1,2
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COMMENTS
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By definition a(n) is also the sum of the divisors of n-th generalized hexagonal number. - Omar E. Pol, Nov 24 2015
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LINKS
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FORMULA
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EXAMPLE
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a(4)=18 because the sum of divisors of the 4th triangular number (i.e., 10) is 1 + 2 + 5 + 10 = 18.
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MATHEMATICA
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Table[DivisorSigma[1, n*(n + 1)/2], {n, 1, 100}] (* Vaclav Kotesovec, Aug 18 2021 *)
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PROG
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(PARI) a(n) = sigma(n*(n+1)/2); \\ Altug Alkan, Nov 24 2015
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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