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Numbers with an odd number of 1's in base 6 expansion.
1

%I #7 Feb 13 2017 00:18:22

%S 1,6,8,9,10,11,13,19,25,31,36,38,39,40,41,43,48,50,51,52,53,54,56,57,

%T 58,59,60,62,63,64,65,66,68,69,70,71,73,78,80,81,82,83,85,91,97,103,

%U 109,114,116,117,118,119,121,127,133,139,145,150,152,153,154,155,157,163

%N Numbers with an odd number of 1's in base 6 expansion.

%C This is to A007092 (numbers in base 6) as A000069 (odious numbers: odd number of 1's in binary expansion) is to A007088 (numbers written in base 2) and as A137469 is to A007091 (numbers in base 5). Note that odd number of 1's in base 3 expansion is simply the odd numbers. This sequence includes, as a subset, A043373 = numbers n such that number of 1's in base 6 is 1.

%C This is strictly different from A043373.

%C Terms in this sequence but not in A043374 are 43, 223, 253, 258, 260, 261, 262, 263, 265, 271, 277, 283, 295, ... - _R. J. Mathar_, May 13 2008

%H <a href="/index/Ar#6-automatic">Index entries for 6-automatic sequences</a>.

%e a(1) = 1 because 1 base 10 = 1 base 6, which has an odd number (1) of ones.

%e a(2) = 6 because 6 base 10 = 10 base 6, which has an odd number (1) of ones.

%e a(3) = 8 because 8 base 10 = 12 base 6, which has an odd number (1) of ones.

%e a(11) = 36 because 36 base 10 = 100 base 6, which has an odd number (1) of ones.

%e a(17) = 43 because 43 base 10 = 111 base 6, which has an odd number (3) of ones.

%p isA138103 := proc(n) local a; a := 0 ; for d in convert(n,base,6) do if d = 1 then a := a+1 ; fi ; od: RETURN( a mod 2 = 1) ; end: for n from 1 to 300 do if isA138103(n) then printf("%d,",n) ; fi ; od: # _R. J. Mathar_, May 13 2008

%Y Cf. A000069, A007088, A007092, A043373, A137469.

%K base,easy,nonn,less

%O 1,2

%A _Jonathan Vos Post_, May 03 2008

%E Corrected and extended by _R. J. Mathar_, May 13 2008