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 A344511 a(n) = Sum_{k >= 0} sign(d_k) * 2^k for any number n with decimal expansion Sum_{k >= 0} d_k * 10^k. 2
 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,11 COMMENTS The binary expansion of a(n) encodes the nonzero digits of the decimal expansion of n. LINKS Rémy Sigrist, Table of n, a(n) for n = 0..8191 FORMULA a(n) belongs to A140900 iff n belongs to A343452. a(A007088(n)) = n. EXAMPLE For n = 20!: - 2432902008176640000 is the decimal expansion of 20!, so   1111101001111110000 is the binary expansion of a(20!), - a(20!) = 513008. PROG (PARI) a(n) = fromdigits(apply(sign, digits(n)), 2) (Python) def a(n): return int("".join((('1' if d!='0' else '0') for d in str(n))), 2) print([a(n) for n in range(87)]) # Michael S. Branicky, May 22 2021 CROSSREFS Cf. A007088, A140900, A289831 (base-3 analog), A343452. Sequence in context: A192454 A340944 A270533 * A244919 A158799 A157532 Adjacent sequences:  A344508 A344509 A344510 * A344512 A344513 A344514 KEYWORD nonn,base AUTHOR Rémy Sigrist, May 21 2021 STATUS approved

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Last modified July 27 11:04 EDT 2021. Contains 346304 sequences. (Running on oeis4.)