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A030690
Smallest nontrivial extension of n-th square which is a cube.
4
125, 4096, 9261, 166375, 250047, 3652264, 4913, 64000, 8120601, 1000, 12167, 1442897, 16974593, 19683, 225866529, 25672375, 28934443, 3241792, 3616805375, 40001688, 4410944, 4843965888, 529475129, 5764224257
OFFSET
1,1
PROG
(Python)
from gmpy2 import iroot
def A030690(n):
d, nd = 10, 10*n**2
while True:
x = (iroot(nd-1, 3)[0]+1)**3
if x < nd+d:
return int(x)
d *= 10
nd *= 10 # Chai Wah Wu, May 24 2016
CROSSREFS
Cf. A030691.
Sequence in context: A265470 A017331 A264139 * A017451 A241034 A265931
KEYWORD
nonn,base
STATUS
approved