A147771 a(n) = round(n^(n/2)).

1, 2, 5, 16, 56, 216, 907, 4096, 19683, 100000, 534146, 2985984, 17403307, 105413504, 661735514, 4294967296, 28761784748, 198359290368, 1406563064942, 10240000000000, 76436817165460, 584318301411328, 4569515072723572

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. A075364, A066642.

Programs

Mathematica

lst={};Do[AppendTo[lst,Round[(n^n)^(1/2)]],{n,40}];lst
Table[Round[n^(n/2)],{n,30}] (* Harvey P. Dale, Feb 17 2020 *)

Python

from gmpy2 import isqrt_rem
def A147771(n):
    i, j = isqrt_rem(n**n)
    return int(i+int(4*(j-i) >= 1)) # Chai Wah Wu, Aug 16 2016