This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A118732 #16 Jul 11 2025 15:35:29 %S A118732 0,1,2,3,4,5,9,10,11,13,14,16,17,18,20,21,22,25,26,27,30,31,32,34,35, %T A118732 36,39,41,45,48,51,52,53,59,60,61,62,63,65,66,68,69,73,74,76,78,79,80, %U A118732 81,86,87,89,91,92,98,99,100,101,103,105,108,113,114,115,117,118,119,121 %N A118732 Numbers k such that 3^k has odd digit sum. %C A118732 Numbers k such that A000244(k) is in A054684. - _Robert Israel_, Jun 28 2017 %H A118732 Robert Israel, <a href="/A118732/b118732.txt">Table of n, a(n) for n = 1..10000</a> %p A118732 select(t -> convert(convert(3^t,base,10),`+`)::odd, [$0..1000]); # _Robert Israel_, Jun 28 2017 %t A118732 Select[Range[0, 121], Mod[ Plus @@ IntegerDigits[3^# ], 2] == 1 &] (* _Ray Chandler_, Jun 10 2006 *) %t A118732 Select[Range[0,200],OddQ[Total[IntegerDigits[3^#]]]&] (* _Harvey P. Dale_, Dec 30 2021 *) %o A118732 (PARI) isok(n) = (sumdigits(3^n) % 2) == 1; \\ _Michel Marcus_, Jun 28 2017 %Y A118732 Cf. A000244, A054684, A118731, A118735. %K A118732 base,nonn %O A118732 1,3 %A A118732 _Zak Seidov_, May 22 2006