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%I #29 Sep 08 2022 08:46:15
%S 1,1,2,4,6,36,42,1764,1806,3261636,3263442,10650053687364,
%T 10650056950806,113423713055411194304049636,
%U 113423713055421844361000442,12864938683278671740537145884937248491231415124195364,12864938683278671740537145998360961546653259485195806
%N a(0) = a(1) = 1; thereafter a(n) = a(n-1) + a(n-2) if n is even, otherwise a(n) = a(n-1)^2.
%C The first bisection is A007018, the second bisection is A174864 (with an only initial 1).
%C After 2, all terms belong to A238411.
%F a(n) = ( 1 + Sum_{k=0..floor(n/2)-1} a(2*k+1) )^(3-(-1)^n)/2 for n>1.
%t a[n_] := If[OddQ@n, a[n - 1] + a[n - 2], a[n - 1]^2]; a[0] = 1; Array[a, 17]
%o (Magma) [n le 2 select 1 else IsEven(n) select Self(n-1)^2 else Self(n-1)+Self(n-2): n in [1..20]];
%Y Cf. A007018, A174864, A238411.
%K nonn
%O 0,3
%A _Vincenzo Librandi_, Feb 23 2016
%E Edited and extended by _Bruno Berselli_, Feb 25 2016
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