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

0,2

Links

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

Formula

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

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 *)

Prog

(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

Crossrefs

Cf. A011095.

Sequence in context: A072944 A024722 A024965 * A173697 A017986 A343304

Adjacent sequences: A018139 A018140 A018141 * A018143 A018144 A018145

Keyword

nonn,easy

Author

N. J. A. Sloane

Status

approved