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%I #21 May 15 2021 06:16:58
%S 0,0,0,0,1,0,0,0,1,0,0,0,1,0,0,0,3,2,2,2,1,0,0,0,1,0,0,0,1,0,0,0,3,2,
%T 2,2,1,0,0,0,1,0,0,0,1,0,0,0,3,2,2,2,1,0,0,0,1,0,0,0,1,0,0,0,7,6,6,6,
%U 5,4,4,4,5,4,4,4,5,4,4,4,3,2,2,2,1,0,0,0,1,0,0,0,1,0,0,0,3,2,2,2,1,0,0,0,1,0,0,0,1,0,0,0,3,2,2,2,1,0,0,0,1
%N A binary encoding of the zeros in base-4 representation of n.
%H Antti Karttunen, <a href="/A292370/b292370.txt">Table of n, a(n) for n = 0..65536</a>
%H <a href="/index/Bi#binary">Index entries for sequences related to binary expansion of n</a>
%F For all n >= 0, A000120(a(n)) = A160380(n).
%e n a(n) base-4(n) binary(a(n))
%e A007090(n) A007088(a(n))
%e -- ---- ---------- ------------
%e 1 0 1 0
%e 2 0 2 0
%e 3 0 3 0
%e 4 1 10 1
%e 5 0 11 0
%e 6 0 12 0
%e 7 0 13 0
%e 8 1 20 1
%e 9 0 21 0
%e 10 0 22 0
%e 11 0 23 0
%e 12 1 30 1
%e 13 0 31 0
%e 14 0 32 0
%e 15 0 33 0
%e 16 3 100 11
%e 17 2 101 10
%t Table[FromDigits[IntegerDigits[n, 4] /. k_ /; IntegerQ@ k :> If[k == 0, 1, 0], 2], {n, 0, 120}] (* _Michael De Vlieger_, Sep 21 2017 *)
%o (Scheme) (define (A292370 n) (if (zero? n) n (let loop ((n n) (b 1) (s 0)) (if (< n 4) s (let ((d (modulo n 4))) (if (zero? d) (loop (/ n 4) (+ b b) (+ s b)) (loop (/ (- n d) 4) (+ b b) s)))))))
%o (Python)
%o from sympy.ntheory.factor_ import digits
%o def a(n):
%o k=digits(n, 4)[1:]
%o return 0 if n==0 else int("".join('1' if i==0 else '0' for i in k), 2)
%o print([a(n) for n in range(111)]) # _Indranil Ghosh_, Sep 21 2017
%Y Cf. A007088, A007090, A160380, A292371, A292372, A292373.
%Y Cf. A291770 (analogous sequence for base-3).
%K nonn,base
%O 0,17
%A _Antti Karttunen_, Sep 15 2017