A030688 Smallest nontrivial extension of n-th square which is a square not ending 00.

16, 49, 961, 169, 256, 361, 49284, 64009, 81225, 100489, 121104, 1444, 169744, 196249, 225625, 256036, 289444, 3249, 361201, 400689, 4414201, 484416, 529984, 576081, 625681, 6765201, 729316, 784996, 8415801, 900601, 9616201

Offset

1,1

Links

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

Prog

(Python)
from gmpy2 import isqrt
def A030688(n):
    d, nd = 10, 10*n**2
    while True:
        x = isqrt(nd-1)+1
        if not x % 10:
            x += 1
        x = x**2
        if x < nd+d:
            return int(x)
        d *= 10
        nd *= 10 # Chai Wah Wu, May 24 2016

Crossrefs

Cf. A030689.

Sequence in context: A104992 A153483 A030686 * A235962 A235573 A186850

Adjacent sequences: A030685 A030686 A030687 * A030689 A030690 A030691

Keyword

nonn,base

Author

Patrick De Geest

Status

approved