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A264786
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Let { d_1, d_2, ..., d_k } be the divisors of n. Then a(n) = d_k^1 + d_(k-1)^2 + ... + d_1^k.
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0
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1, 3, 4, 9, 6, 24, 8, 33, 19, 44, 12, 226, 14, 72, 68, 161, 18, 429, 20, 534, 98, 152, 24, 3858, 51, 204, 136, 856, 30, 6534, 32, 1089, 182, 332, 210, 22965, 38, 408, 236, 12886, 42, 14262, 44, 2148, 1868, 584, 48, 128338, 99, 2333, 368, 3214, 54, 21810, 302
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OFFSET
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1,2
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LINKS
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EXAMPLE
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For n = 4: a(4) = 4^1 + 2^2 + 1^3 = 9.
For n = 5: a(5) = 5^1 + 1^2 = 6.
For n = 6: a(6) = 6^1 + 3^2 + 2^3 + 1^4 = 24.
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MATHEMATICA
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a[n_] := Sum[Sort[Divisors[n], #1 > #2 &][[i]]^i, {i, DivisorSigma[0, n]}]; Table[a[n], {n, 60}]
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PROG
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(PARI) a(n) = my(d = divisors(n)); sum(k=1, #d, d[k]^(#d-k+1)); \\ Michel Marcus, Jan 01 2016
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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