[seqfan] n and n^2 use digits 0,1,4,6 only: A136859 - a question

[Neil Sloane]

A136859 contains the numbers n such that n and n^2 use only the digits
0,1,4,6.

It appears that n must be 0, 10^k, or 4*10^k. Does anyone know if this is a
theorem?

I don't know how far it has been checked.

The entry had a formula which was based on there being no other type of
term, but this was only a conjecture.  I deleted the program and the b-file
that were based on the conjecture.

Thanks to Maximilian for raising suspicions about the formula.

It would be nice if someone could check that the terms shown are complete,
that there are no missing numbers. The terms shown are the original ones
found by Jonathan Wellons, so they are probably correct, but it would be
good to have a check.