cp's OEIS Frontend

A230639 Let M(1)=0 and for n>1, B(n)=(M(ceiling(n/2))+M(floor(n/2))+2)/2, M(n)=3^B(n)+M(floor(n/2))+1. This sequence gives B(n).

%I A230639 #33 Sep 05 2024 15:38:44
%S A230639 1,3,5,17,29,139,249,64570209,129140169,34315253252541,68630377364913,
%T A230639 1044297913696328396542704032390321722034449074468444246791788357605,
%U A230639 2088595827392656793085408064780643444068898148936888424953199350297
%N A230639 Let M(1)=0 and for n>1, B(n)=(M(ceiling(n/2))+M(floor(n/2))+2)/2, M(n)=3^B(n)+M(floor(n/2))+1. This sequence gives B(n).
%C A230639 The largest power of 3 in M(n) = A230640(n).
%H A230639 Max Alekseyev, <a href="/A230639/a230639.txt">Table n, expression for a(n) for n=2..100</a>
%H A230639 Max A. Alekseyev and N. J. A. Sloane, <a href="https://arxiv.org/abs/2112.14365">On Kaprekar's Junction Numbers</a>, arXiv:2112.14365, 2021; Journal of Combinatorics and Number Theory 12:3 (2022), 115-155.
%H A230639 <a href="/index/Coi#Colombian">Index entries for Colombian or self numbers and related sequences</a>
%p A230639 f:=proc(n) option remember; local B, M;
%p A230639 if n<=1 then RETURN([0, 0]);
%p A230639 else
%p A230639 B:=(f(ceil(n/2))[2] + f(floor(n/2))[2] + 2)/2;
%p A230639 M:=3^B+f(floor(n/2))[2]+1; RETURN([B, M]); fi;
%p A230639 end proc;
%p A230639 [seq(f(n)[1], n=1..9)];
%Y A230639 Cf. A230093, A230640 (for M(n)).
%Y A230639 Related base-3 sequences: A053735, A134451, A230641, A230642, A230643, A230853, A230854, A230855, A230856, A230639, A230640, A010063 (trajectory of 1)
%K A230639 nonn,base
%O A230639 2,2
%A A230639 _N. J. A. Sloane_, Oct 31 2013
%E A230639 Terms a(10) onward from _Max Alekseyev_, Nov 02 2013