A061277 Numbers which have more different digits than their squares.

109, 173, 235, 264, 1049, 1235, 1485, 1489, 1490, 1498, 1703, 1730, 1823, 1834, 2107, 2108, 2350, 2357, 2435, 2538, 2581, 2640, 2830, 2978, 2980, 2983, 3114, 3148, 3157, 3408, 4827, 5162, 5470, 5480, 5962, 6380, 6498, 6742, 6912, 7450, 8130, 8167, 9235, 9607

Offset

1,1

Comments

The sequence is infinite since for every element k with '0' as last digit or no '0' at all every k*10^m is also in it.

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000

Example

3114 is okay, since it has three different digits while 3114^2 = 9696996 has only two.

Mathematica

Select[Range[6000], Count[DigitCount[#], 0]<Count[DigitCount[#^2], 0]&] (* Harvey P. Dale, Jul 19 2019 *)

Prog

(PARI) isok(n) = length(Set(digits(n, 10))) > length(Set(digits(n^2, 10))) \\ Michel Marcus, Jul 22 2013
(Python)
def ok(n): return len(set(str(n))) > len(set(str(n**2)))
print([k for k in range(10**4) if ok(k)]) # Michael S. Branicky, Apr 20 2023

Crossrefs

Sequence in context: A141948 A102908 A141998 * A142945 A142079 A142224

Adjacent sequences: A061274 A061275 A061276 * A061278 A061279 A061280

Keyword

nonn,base

Author

Ulrich Schimke (ulrschimke(AT)aol.com)

Extensions

a(36) and beyond from Michael S. Branicky, Apr 20 2023

Status

approved