A045860 Numbers whose square has initial digit '6'.

8, 25, 26, 78, 79, 80, 81, 82, 83, 245, 246, 247, 248, 249, 250, 251, 252, 253, 254, 255, 256, 257, 258, 259, 260, 261, 262, 263, 264, 775, 776, 777, 778, 779, 780, 781, 782, 783, 784, 785, 786, 787, 788, 789, 790, 791, 792, 793, 794, 795, 796, 797, 798, 799

Offset: 1

Author

Jeff Burch

Keywords

• nonn
• base

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Supersequence of A035073.

Cf. A045789.

Programs

Mathematica

Flatten[Table[Range[Ceiling[Sqrt[6*10^n]],Floor[Sqrt[7*10^n]]],{n,5}]] (* Harvey P. Dale, Apr 03 2013 *)

Python

from math import isqrt
def aupto(limit):
    alst, d, end = [], 1, 0
    while end < limit:
        start, end = isqrt(6*10**d) + 1, isqrt(7*10**d-1)
        alst.extend([an for an in list(range(start, end+1)) if an <= limit])
        d += 1
    return alst
print(aupto(799)) # Michael S. Branicky, Aug 25 2021