A018142 Powers of fifth root of 10 rounded to nearest integer.

1, 2, 3, 4, 6, 10, 16, 25, 40, 63, 100, 158, 251, 398, 631, 1000, 1585, 2512, 3981, 6310, 10000, 15849, 25119, 39811, 63096, 100000, 158489, 251189, 398107, 630957, 1000000, 1584893, 2511886, 3981072, 6309573

Offset: 0

Author

N. J. A. Sloane

Keywords

• nonn
• easy

Links

• Chai Wah Wu, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A011095.

Programs

Maple

A018142:=n->round(10^(n/5)): seq(A018142(n), n=0..50); # Wesley Ivan Hurt, Jun 23 2015

Mathematica

Round[(10^(Range[0, 50]/5))] (* Paolo Xausa, Jul 02 2024 *)
Round[Surd[10,5]^Range[0,50]] (* Harvey P. Dale, Jan 29 2025 *)

Python

from gmpy2 import iroot_rem
def A018142(n):
    i,j = iroot_rem(10**n,5)
    return int(i) + int(32*j >= 10*i*(4*i*(2*i*(i + 1) + 1) + 1) + 1) # Chai Wah Wu, Aug 18 2016

Formula

a(n) = round(10^(n/5)). - Wesley Ivan Hurt, Jun 23 2015