A030697 Smallest nontrivial extension of n-th cube which is a cube not ending 000.

125, 85184, 2744, 6434856, 1259712, 2161700757, 34328125, 5124031424, 7290099019, 10007873875, 13312053, 172808693, 21975528401, 274498269499, 337589698347, 409675763483, 491355848971, 58320792152, 68593724400375

Offset

1,1

Links

Chai Wah Wu, Table of n, a(n) for n = 1..10000

Prog

(Python)
from gmpy2 import iroot
def A030697(n):
    d, nd = 10, 10*n**3
    while True:
        x = iroot(nd-1, 3)[0]+1
        if not x % 10:
            x += 1
        x = x**3
        if x < nd+d:
            return int(x)
        d *= 10
        nd *= 10 # Chai Wah Wu, May 24 2016

Crossrefs

Cf. A030698.

Sequence in context: A194654 A222277 A013783 * A265623 A050640 A161354

Adjacent sequences: A030694 A030695 A030696 * A030698 A030699 A030700

Keyword

nonn,base

Author

Patrick De Geest

Status

approved