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 A318439 For any n >= 0 with binary expansion Sum_{k=0..w} b_k * 2^k, let h(n) = Sum_{k=0..w) b_k * (i-1)^k (where i denotes the imaginary unit); a(n) is the imaginary part of h(n). 3
 0, 0, 1, 1, -2, -2, -1, -1, 2, 2, 3, 3, 0, 0, 1, 1, 0, 0, 1, 1, -2, -2, -1, -1, 2, 2, 3, 3, 0, 0, 1, 1, -4, -4, -3, -3, -6, -6, -5, -5, -2, -2, -1, -1, -4, -4, -3, -3, -4, -4, -3, -3, -6, -6, -5, -5, -2, -2, -1, -1, -4, -4, -3, -3, 8, 8, 9, 9, 6, 6, 7, 7, 10 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,5 COMMENTS See A318438 for the real part of h and additional comments. LINKS Rémy Sigrist, Table of n, a(n) for n = 0..10000 FORMULA a(2^k) = A108520(k-1) for any k > 0. PROG (PARI) a(n) = my (d=Vecrev(digits(n, 2))); imag(sum(i=1, #d, d[i]*(I-1)^(i-1))) CROSSREFS Cf. A108520, A318438. Sequence in context: A153864 A112399 A165123 * A106180 A274369 A055091 Adjacent sequences:  A318436 A318437 A318438 * A318440 A318441 A318442 KEYWORD sign,look,base AUTHOR Rémy Sigrist, Aug 26 2018 STATUS approved

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Last modified January 26 11:13 EST 2020. Contains 331279 sequences. (Running on oeis4.)