A269265 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.

1, 1, 2, 4, 6, 36, 42, 1764, 1806, 3261636, 3263442, 10650053687364, 10650056950806, 113423713055411194304049636, 113423713055421844361000442, 12864938683278671740537145884937248491231415124195364, 12864938683278671740537145998360961546653259485195806

Offset

0,3

Comments

The first bisection is A007018, the second bisection is A174864 (with an only initial 1).

After 2, all terms belong to A238411.

Links

Table of n, a(n) for n=0..16.

Formula

a(n) = ( 1 + Sum_{k=0..floor(n/2)-1} a(2*k+1) )^(3-(-1)^n)/2 for n>1.

Mathematica

a[n_] := If[OddQ@n, a[n - 1] + a[n - 2], a[n - 1]^2]; a[0] = 1; Array[a, 17]

Prog

(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]];

Crossrefs

Cf. A007018, A174864, A238411.

Sequence in context: A045662 A195324 A175877 * A173818 A263541 A283157

Adjacent sequences: A269262 A269263 A269264 * A269266 A269267 A269268

Keyword

nonn

Author

Vincenzo Librandi, Feb 23 2016

Extensions

Edited and extended by Bruno Berselli, Feb 25 2016

Status

approved