A147773 a(n) = round((n^n)^(1/3)).

1, 2, 3, 6, 15, 36, 94, 256, 729, 2154, 6583, 20736, 67156, 223150, 759375, 2642246, 9387369, 34012224, 125537306, 471556032, 1801088541, 6989288907, 27536796143, 110075314176, 446169698824, 1832746290156, 7625597484987, 32122422687591

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Nov 12 2008

Keywords

• nonn

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..500

Crossrefs

Cf. A105209, A000312.

Programs

Mathematica

lst={};Do[AppendTo[lst,Round[(n^n)^(1/3)]],{n,40}];lst

Python

from gmpy2 import iroot_rem
def A147773(n):
    i, j = iroot_rem(n**n,3)
    return int(i+int(8*j >= 6*i*(2*i+1)+1)) # Chai Wah Wu, Aug 16 2016

Formula

a(n) = A105209(A000312(n)). - Michel Marcus, Aug 19 2016