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A239935
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Numbers k such that DigitSum(3^k) > DigitSum(3^(k+1)).
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2
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11, 14, 15, 18, 20, 27, 29, 31, 34, 38, 41, 43, 47, 48, 50, 53, 54, 58, 59, 63, 64, 65, 67, 69, 71, 72, 75, 77, 79, 83, 88, 90, 94, 98, 99, 102, 103, 107, 109, 112, 114, 118, 119, 123, 125, 131, 132, 134, 136, 139, 141, 142, 146, 150, 154, 159, 161, 164, 167
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OFFSET
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1,1
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LINKS
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EXAMPLE
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For k=11, we have DigitSum(3^11) = 27 > 18 = DigitSum(3^12).
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MAPLE
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N:= 1000: # to get the first N terms
threen:= 3:
digsum:= 3:
count:= 0:
for n from 1 while count < N do
threen:= 3*threen;
oldsum:= digsum;
digsum:= convert(convert(threen, base, 10), `+`);
if oldsum > digsum then
count:= count+1;
fi
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MATHEMATICA
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lis = Table[Total[IntegerDigits[3^n, 10]], {n, 1, 100}];
Flatten[Position[Greater @@@ Partition[lis, 2, 1], True]]
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PROG
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(PARI) isok(k) = sumdigits(3^k) > sumdigits(3^(k+1)); \\ Michel Marcus, Jul 03 2021
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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