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A005469 a(n) = 1 + a(floor(n/2))*a(ceiling(n/2)) for n > 1, a(1) = 2.

%I A005469 M1398 #21 Nov 16 2020 12:10:33
%S A005469 2,5,11,26,56,122,287,677,1457,3137,6833,14885,35015,82370,194300,
%T A005469 458330,986390,2122850,4570610,9840770,21435122,46689890,101709206,
%U A005469 221563226,521198276,1226050226,2884185551,6784816901,16004491001,37752490001,89053519001
%N A005469 a(n) = 1 + a(floor(n/2))*a(ceiling(n/2)) for n > 1, a(1) = 2.
%D A005469 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%p A005469 a:= proc(n) option remember; `if`(n=1, 2,
%p A005469       1+(t->a(t)*a(n-t))(iquo(n, 2)))
%p A005469     end:
%p A005469 seq(a(n), n=1..35);  # _Alois P. Heinz_, Jul 04 2019
%t A005469 a[n_] := a[n] = If[n==1, 2, 1 + a[Floor[n/2]] a[Ceiling[n/2]]];
%t A005469 a /@ Range[35] (* _Jean-François Alcover_, Nov 16 2020 *)
%Y A005469 Cf. A005468.
%K A005469 nonn
%O A005469 1,1
%A A005469 _Colin Mallows_