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A366578
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Sum of the divisors of 3^n+1.
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11
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3, 7, 18, 56, 126, 434, 1332, 3836, 10476, 42560, 109926, 315112, 816732, 2790074, 8906760, 30220288, 64570086, 229156928, 706911048, 2034690952, 5357742012, 21838961760, 56496274632, 164750562956, 456919958880, 1517043139136, 4661686010664, 16489453890560
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OFFSET
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0,1
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LINKS
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FORMULA
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EXAMPLE
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a(4)=126 because 3^4+1 has divisors {1, 2, 41, 82}.
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MAPLE
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a:=n->numtheory[sigma](3^n+1):
seq(a(n), n=0..100);
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MATHEMATICA
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DivisorSigma[1, 3^Range[0, 30]+1] (* Paolo Xausa, Oct 15 2023 *)
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CROSSREFS
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Cf. A000203, A002592, A024023, A057935, A057941, A074476, A075708, A274909, A366576, A366577, A366579, A366580
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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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