A165428 a(1) = 1, a(2) = 10; thereafter a(n) = Product_{1 <= i <= n-1} a(i).

1, 10, 10, 100, 10000, 100000000, 10000000000000000, 100000000000000000000000000000000, 10000000000000000000000000000000000000000000000000000000000000000

Offset: 1

Author

Jaroslav Krizek, Sep 17 2009

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 1..12

Programs

Mathematica

a[1] = 1; a[2] = 10; a[n_] := Times @@ Array[a, n - 1]; Array[a, 9] (* Robert G. Wilson v, Oct 13 2009 *)
Join[{1,10},NestList[#^2&,10,10]] (* Harvey P. Dale, Nov 30 2021 *)

PARI

{a(n) = if(n==1, 1, if(n==2, 10, prod(j=1,n-1, a(j))))};
for(n=1,10, print1(a(n), ", ")) \\ G. C. Greubel, Oct 19 2018

Formula

a(n) = 10^(2^(n-3)) = A011557(2^(n-3)) = 10^A000079(n-3).

a(1) = 1, a(2) = 10, a(3) = 10, and for n > 3 a(n) = (a(n-1))^2.

Extensions

Name changed, formula edited by Robert G. Wilson v, Oct 13 2009

Edited by N. J. A. Sloane, Oct 15 2009