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).

1, 3, 5, 17, 29, 139, 249, 64570209, 129140169, 34315253252541, 68630377364913, 1044297913696328396542704032390321722034449074468444246791788357605, 2088595827392656793085408064780643444068898148936888424953199350297

Offset

2,2

Comments

The largest power of 3 in M(n) = A230640(n).

Links

Table of n, a(n) for n=2..14.

Max Alekseyev, Table n, expression for a(n) for n=2..100

Max A. Alekseyev and N. J. A. Sloane, On Kaprekar's Junction Numbers, arXiv:2112.14365, 2021; Journal of Combinatorics and Number Theory 12:3 (2022), 115-155.

Index entries for Colombian or self numbers and related sequences

Maple

f:=proc(n) option remember; local B, M;
if n<=1 then RETURN([0, 0]);
else
B:=(f(ceil(n/2))[2] + f(floor(n/2))[2] + 2)/2;
M:=3^B+f(floor(n/2))[2]+1; RETURN([B, M]); fi;
end proc;
[seq(f(n)[1], n=1..9)];

Crossrefs

Cf. A230093, A230640 (for M(n)).

Related base-3 sequences: A053735, A134451, A230641, A230642, A230643, A230853, A230854, A230855, A230856, A230639, A230640, A010063 (trajectory of 1)

Sequence in context: A350856 A174913 A079496 * A038898 A333353 A297175

Adjacent sequences: A230636 A230637 A230638 * A230640 A230641 A230642

Keyword

nonn,base

Author

N. J. A. Sloane, Oct 31 2013

Extensions

Terms a(10) onward from Max Alekseyev, Nov 02 2013

Status

approved