A175138 a(n) = Product_{i=1..n-1} a(i), with a(1) = 3 and a(2) = 5.

3, 5, 15, 225, 50625, 2562890625, 6568408355712890625, 43143988327398919500410556793212890625, 1861403728794734215467410604755702820123364205073812627233564853668212890625

Offset

1,1

Comments

Except for first three terms, a(n) = (a(n-1))^2.

Links

Table of n, a(n) for n=1..9.

Formula

a(n) = 15^(2^(n-3)), n > 2.

Product_{n>=1} (1 + 1/a(n)) = 12/7. - Amiram Eldar, Nov 30 2025

Mathematica

Join[{3, 5}, NestList[#^2&, 15, 7]] (* Harvey P. Dale, Feb 08 2013 *)

Crossrefs

Sequence in context: A270548 A292339 A374463 * A248795 A382519 A215444

Adjacent sequences: A175135 A175136 A175137 * A175139 A175140 A175141

Keyword

nonn,easy

Author

Giovanni Teofilatto, Feb 23 2010

Extensions

Edited by Jaroslav Krizek and R. J. Mathar, Mar 04 2010

Status

approved