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A118872
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Numbers k such that digit sum of 3^k is a power of 3.
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4
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0, 1, 2, 3, 4, 5, 9, 10, 11, 13, 16, 17, 21, 27, 31, 35, 36, 39, 114, 119, 973, 1005, 1010, 1025, 3006, 3029, 3040, 9128, 9215, 9227, 9316, 27431, 27442, 27515, 27519, 27554, 82632, 82746, 82763, 82784, 83111, 246838, 247206, 247388, 247406, 247447, 741310, 742154
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OFFSET
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1,3
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COMMENTS
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a(47) <= 741310. If a(47) < 741310 then a(47) < 720000. a(48) <= 742154. If a(48) < 741310 then a(48) < 720000. - David A. Corneth, Nov 23 2022
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LINKS
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FORMULA
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EXAMPLE
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3^39 = 4052555153018976267 with digit sum 81 = 3^4, so 39 is a term.
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MATHEMATICA
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Do[If[IntegerQ[Log[3, Plus @@ IntegerDigits[3^n]]], Print[n]], {n, 0, 677750}];
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PROG
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(PARI) is(n) = my(s = sumdigits(3^n)); s == 3^logint(s, 3) \\ David A. Corneth, Nov 23 2022
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CROSSREFS
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Cf. A004166 (sum of digits of 3^n).
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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