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A230640 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 M(n). 20
0, 4, 28, 248, 129140168, 68630377364912, 2088595827392656793085408064780643444068898148936888424953199350296 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

Max A. Alekseyev, Donovan Johnson and N. J. A. Sloane, On Kaprekar's Junction Numbers, in preparation, 2017.

LINKS

Table of n, a(n) for n=1..7.

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)[2], n=1..7)];

CROSSREFS

Cf. A230639.

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

Smallest number m such that u + (sum of base-b digits of u) = m has exactly n solutions, for bases 2 through 10: A230303, A230640, A230638, A230867, A238840, A238841, A238842, A238843, A006064.

Sequence in context: A103211 A229644 A228714 * A300050 A191801 A064340

Adjacent sequences:  A230637 A230638 A230639 * A230641 A230642 A230643

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane, Oct 31 2013

STATUS

approved

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Last modified September 15 12:22 EDT 2019. Contains 327078 sequences. (Running on oeis4.)