cp's OEIS Frontend

A060585 Write n in base 3, then (working from left to right) if the k-th digit of n is not equal to the digit to its left then the k-th digit of a(n) is 1, otherwise it is 0, and finally read the result as a base-2 number.

%I A060585 #14 Apr 15 2021 23:37:48
%S A060585 0,1,1,3,2,3,3,3,2,6,7,7,5,4,5,7,7,6,6,7,7,7,6,7,5,5,4,12,13,13,15,14,
%T A060585 15,15,15,14,10,11,11,9,8,9,11,11,10,14,15,15,15,14,15,13,13,12,12,13,
%U A060585 13,15,14,15,15,15,14,14,15,15,13,12,13,15,15,14,10,11,11,11,10,11,9,9
%N A060585 Write n in base 3, then (working from left to right) if the k-th digit of n is not equal to the digit to its left then the k-th digit of a(n) is 1, otherwise it is 0, and finally read the result as a base-2 number.
%C A060585 A ternary-to-binary map.
%C A060585 Each k appears A001316(k) times in the sequence.
%F A060585 a(n) = 2*a(floor(n/3)) + A060584(n) = A060586(A060587(n)).
%e A060585 a(76) = 10 since 76 = 2211_3 and looking for changing digits produces 1010 which, read as if in binary, is 10.
%o A060585 (PARI) a(n) = my(v=digits(n,3)); if(#v, forstep(k=#v,2,-1, v[k]=(v[k]!=v[k-1])); v[1]=1); fromdigits(v,2); \\ _Kevin Ryde_, Apr 15 2021
%Y A060585 Cf. A001316, A060584, A060586, A060587.
%K A060585 base,nonn
%O A060585 0,4
%A A060585 _Henry Bottomley_, Apr 04 2001
%E A060585 Definition rewritten by Editors of OEIS, Apr 15 2021.