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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 LINKS Max A. Alekseyev and N. J. A. Sloane, On Kaprekar's Junction Numbers, arXiv:2112.14365, 2021; Journal of Combinatorics and Number Theory, 2022 (to appear). 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: A229644 A354602 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 February 1 09:28 EST 2023. Contains 359992 sequences. (Running on oeis4.)