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 A289814 A binary encoding of the twos in ternary representation of n (see Comments for precise definition). 30
 0, 0, 1, 0, 0, 1, 2, 2, 3, 0, 0, 1, 0, 0, 1, 2, 2, 3, 4, 4, 5, 4, 4, 5, 6, 6, 7, 0, 0, 1, 0, 0, 1, 2, 2, 3, 0, 0, 1, 0, 0, 1, 2, 2, 3, 4, 4, 5, 4, 4, 5, 6, 6, 7, 8, 8, 9, 8, 8, 9, 10, 10, 11, 8, 8, 9, 8, 8, 9, 10, 10, 11, 12, 12, 13, 12, 12, 13, 14, 14, 15, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,7 COMMENTS The ones in the binary representation of a(n) correspond to the twos in the ternary representation of n; for example: ternary(42) = 1120 and binary(a(42)) = 10 (a(42) = 2). See A289813 for the sequence encoding the ones in ternary representation of n and additional comments. LINKS Rémy Sigrist, Table of n, a(n) for n = 0..6560 FORMULA a(0) = 0. a(3*n) = 2 * a(n). a(3*n+1) = 2 * a(n). a(3*n+2) = 2 * a(n) + 1. Also, a(n) = A289813(A004488(n)). A053735(n) = A000120(A289813(n)) + 2*A000120(a(n)). - Antti Karttunen, Jul 20 2017 EXAMPLE The first values, alongside the ternary representation of n, and the binary repesentation of a(n), are: n       a(n)    ternary(n)  binary(a(n)) --      ----    ----------  ------------ 0       0       0           0 1       0       1           0 2       1       2           1 3       0       10          0 4       0       11          0 5       1       12          1 6       2       20          10 7       2       21          10 8       3       22          11 9       0       100         0 10      0       101         0 11      1       102         1 12      0       110         0 13      0       111         0 14      1       112         1 15      2       120         10 16      2       121         10 17      3       122         11 18      4       200         100 19      4       201         100 20      5       202         101 21      4       210         100 22      4       211         100 23      5       212         101 24      6       220         110 25      6       221         110 26      7       222         111 MATHEMATICA Table[FromDigits[#, 2] &[IntegerDigits[n, 3] /. d_ /; d > 0 :> d - 1], {n, 0, 81}] (* Michael De Vlieger, Jul 20 2017 *) PROG (PARI) a(n) = my (d=digits(n, 3)); fromdigits(vector(#d, i, if (d[i]==2, 1, 0)), 2) (Python) from sympy.ntheory.factor_ import digits def a(n):     d=digits(n, 3)[1:]     return int("".join(['1' if i==2 else '0' for i in d]), 2) print map(a, xrange(101)) # Indranil Ghosh, Jul 20 2017 CROSSREFS Cf. A000120, A053735, A289813. Sequence in context: A244442 A246471 A079243 * A304760 A304759 A073438 Adjacent sequences:  A289811 A289812 A289813 * A289815 A289816 A289817 KEYWORD nonn,base,look AUTHOR Rémy Sigrist, Jul 12 2017 STATUS approved

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Last modified January 15 20:47 EST 2019. Contains 319184 sequences. (Running on oeis4.)