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Let $a(n)$ be A071585, i.e., numerator of the continued fraction expansion whose terms are the first-order differences of exponents in the binary representation of $4n$, with the exponents of $2$ being listed in descending order.

In the formulas section Yosu Yurramendi gives a nice recurrence: $$a(2^m+k)=a(k)+[0\leqslant k<2^{m-1}]\cdot a(k+2^{m-1})+[2^{m-1}\leqslant k<2^m]\cdot a(k-2^{m-1}), a(0)=1, a(1)=2$$

I conjecture that there also exists another recurrence $$a(n)=a(\left\lfloor\frac{n}{2}\right\rfloor)+a(k)-a(k_1)+a(k_2)-\cdots+(-1)^ma(k_m), a(0)=1$$ where $$n=(2k+1)2^{t_1}$$ $$k=(2k_1+1)2^{t_2}$$ $$k_1=(2k_2+1)2^{t_3}$$ $$\cdots$$ $$k_{m-1}=(2k_m+1)2^{t_{m+1}}$$ $$k_m=0$$ Also obviously $$n=2^{t_1}(1+2^{1+t_2}(1+\dots(1+2^{1+t_\ell}))\dots)$$

Is there a way to prove it?

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    $\begingroup$ Your conjecture is based on what evidence? What numeric computations have you done? $\endgroup$
    – Somos
    Commented Oct 10, 2022 at 16:12
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    $\begingroup$ The question title and the body of the question refer to entirely different sequences. $\endgroup$ Commented Oct 10, 2022 at 17:25
  • $\begingroup$ @Somos, thank you for comment! No counterexamples up to $10^6$. $\endgroup$ Commented Oct 11, 2022 at 4:24
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    $\begingroup$ @StevenStadnicki, thank you for comment! See the last formula for A071585: it uses A007306 and two permutations of natural numbers. $\endgroup$ Commented Oct 11, 2022 at 4:26

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