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A068334
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a(1) = 1; a(n+1) = 1 + Product_{k|n} a(k), product is over the positive divisors, k, of n.
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3
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1, 2, 3, 4, 9, 10, 61, 62, 497, 1492, 26857, 26858, 6445921, 6445922, 786402485, 21232867096, 10531502079617, 10531502079618, 314049392014208761, 314049392014208762, 33736441887734362049089, 6173768865455388254983288
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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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a(7) = 1 + a(1)*a(2)*a(3)*a(6) = 1 + 1*2*3*10 = 61.
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MATHEMATICA
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Nest[Append[#1, 1 + Times @@ #1[[Divisors[#2] ]] ] & @@ {#, Length[#]} &, {1}, 21] (* Michael De Vlieger, Apr 13 2021 *)
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PROG
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(PARI) lista(nn) = {my(va = vector(nn)); va[1] = 1; for (n=2, nn, my(d=divisors(n-1)); va[n] = 1 + prod(k=1, #d, va[d[k]]); ); va; } \\ Michel Marcus, Apr 13 2021
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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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