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 A289831 a(n) = A289813(n) + A289814(n). 8
 0, 1, 1, 2, 3, 3, 2, 3, 3, 4, 5, 5, 6, 7, 7, 6, 7, 7, 4, 5, 5, 6, 7, 7, 6, 7, 7, 8, 9, 9, 10, 11, 11, 10, 11, 11, 12, 13, 13, 14, 15, 15, 14, 15, 15, 12, 13, 13, 14, 15, 15, 14, 15, 15, 8, 9, 9, 10, 11, 11, 10, 11, 11, 12, 13, 13, 14, 15, 15, 14, 15, 15, 12 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,4 COMMENTS The ones in the binary representation of a(n) correspond to the nonzero digits in the ternary representation of n; for example: ternary(42) = 1120 and binary(a(42)) = 1110 (a(42) = 14). Each number k >= 0 appears 2^A000120(k) times. a(A004488(n)) = a(n). 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) + 1. a(3*n + 2) = 2*a(n) + 1. EXAMPLE The first values, alongside the ternary representation of n, and the binary representation of a(n), are: n       a(n)    ternary(n)  binary(a(n)) --      ----    ----------  ------------ 0       0       0           0 1       1       1           1 2       1       2           1 3       2       10          10 4       3       11          11 5       3       12          11 6       2       20          10 7       3       21          11 8       3       22          11 9       4       100         100 10      5       101         101 11      5       102         101 12      6       110         110 13      7       111         111 14      7       112         111 15      6       120         110 16      7       121         111 17      7       122         111 18      4       200         100 19      5       201         101 20      5       202         101 21      6       210         110 22      7       211         111 23      7       212         111 24      6       220         110 25      7       221         111 26      7       222         111 MATHEMATICA Table[FromDigits[Sign@ IntegerDigits[n, 3], 2], {n, 0, 100}] (* Indranil Ghosh, Aug 03 2017 *) PROG (PARI) a(n) = my (d=digits(n, 3)); fromdigits(vector(#d, i, sign(d[i])), 2) (Python) from sympy.ntheory.factor_ import digits from sympy import sign def a(n):     d=digits(n, 3)[1:]     return int(''.join(str(sign(i)) for i in d), 2) print([a(n) for n in range(101)]) # Indranil Ghosh, Aug 03 2017 CROSSREFS Cf. A000120, A004488, A289813, A289814. Sequence in context: A238756 A025076 A110006 * A335358 A296611 A308661 Adjacent sequences:  A289828 A289829 A289830 * A289832 A289833 A289834 KEYWORD nonn,base AUTHOR Rémy Sigrist, Jul 13 2017 STATUS approved

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Last modified August 8 09:27 EDT 2022. Contains 356005 sequences. (Running on oeis4.)