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A139802
a(1)=1, a(2)=2, a(n)=n^a(n-2).
1
1, 2, 3, 16, 125, 2821109907456, 4337654948097993282537354757263188251697832994620405101744893017744569432720994168089672192211758909320807
OFFSET
1,2
COMMENTS
Exponential double factorial.
The next term is too large to include.
EXAMPLE
a(1)=1;
a(2)=2;
a(3)=3^1=3;
a(4)=4^2=16;
a(5)=5^3=125;
a(6)=6^16=2821109907456;
etc.
MATHEMATICA
a[1]=1; a[2]=2; a[n_]:=n^a[n-2]; Array[a, 7] (* Stefano Spezia, Feb 14 2024 *)
CROSSREFS
Cf. A049384.
Sequence in context: A269067 A370201 A356882 * A292207 A063666 A006247
KEYWORD
easy,nonn
AUTHOR
STATUS
approved