Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #46 Jul 14 2018 17:06:03
%S 2,3,4,5,5,7,7,8,6,9,10,11,9,12,11,13,7,11,13,14,13,17,15,18,11,16,17,
%T 19,14,19,18,21,8,13,16,17,17,22,19,23,16,23,24,27,19,26,25,29,13,20,
%U 23,25,22,29,26,31,17,25,27,30,23,31,29,34,9,15,19,20,21,27,23,28,21,30
%N Bisection of A086592, denominators of the left-hand half of Kepler's tree of fractions.
%C Also denominator of alternate fractions in Kepler's tree as shown in A294442. - _N. J. A. Sloane_, Nov 20 2017
%H Antti Karttunen, <a href="/A086593/b086593.txt">Table of n, a(n) for n = 1..2048</a> (computed from b-file of A020650 provided by _T. D. Noe_)
%F a(n) = A086592(2n-1) = A020650(4n-2).
%F a(n+1) = A071585(n) + A071766(n), n >= 0. - _Yosu Yurramendi_, Jun 30 2014
%F From _Yosu Yurramendi_, Jan 04 2016: (Start)
%F a(2^(m+1)+k+1) - a(2^m+k+1) = A071585(k), m >= 0, 0 <= k < 2^m.
%F a(2^(m+2)-k) = a(2^(m+1)-k) + a(2^m-k), m > 0, 0 <= k < 2^m-1.
%F (End)
%F a(2^n) = A000045(n+3). - _Antti Karttunen_, Jan 29 2016, based on above.
%F a(n) = A020651(4n-1), a(n+1) = A020651(4n+1), n > 0. - _Yosu Yurramendi_, May 08 2018
%F a(2^m+k) = A071585(2^(m+1)+k), m >= 0, 0 <= k < 2^m. - _Yosu Yurramendi_, May 16 2018
%t (* b = A020650 *) b[1] = 1; b[2] = 2; b[3] = 1; b[n_] := b[n] = Switch[ Mod[n, 4], 0, b[n/2 + 1] + b[n/2], 1, b[(n - 1)/2 + 1], 2, b[(n - 2)/2 + 1] + b[(n - 2)/2], 3, b[(n - 3)/2]]; a[1] = 2; a[n_] := b[4 n - 4]; Array[a, 100] (* _Jean-François Alcover_, Jan 22 2016, after _Yosu Yurramendi_'s formula for A020650 *)
%o (R)
%o maxlevel <- 15
%o d <- c(1,2)
%o for(m in 0:maxlevel)
%o for(k in 1:2^m) {
%o d[2^(m+1) +k] <- d[k] + d[2^m+k]
%o d[2^(m+1)+2^m+k] <- d[2^(m+1)+k]
%o }
%o a <- vector()
%o for(m in 0:maxlevel) for(k in 0:(2^m-1)) a[2^m+k] <- d[2^(m+1)+k]
%o a[1:63]
%o # _Yosu Yurramendi_, May 16 2018
%Y Cf. A000045, A020650, A020651, A071585, A071766, A086592, A294442.
%K nonn
%O 1,1
%A _Antti Karttunen_, Aug 28 2003