A137066 Numbers k such that k and k^2 use only the digits 2, 3, 4 and 5.

2, 5, 235, 2335, 23335, 233335, 2333335, 2354235, 23333335, 233333335, 2333333335, 2333524235, 23333333335, 23333524235, 233333333335, 2333333333335, 23333333333335, 233333333333335, 2333333333333335, 23333333333333335, 233333333333333335

Offset

1,1

Comments

Generated with DrScheme.

Contains 2*10^m + (10^m-1)/3 + 2 for m >= 2. Are these all the terms > 23333524235? There are no others with up to 25 digits. - Robert Israel, Jul 02 2018

There are no others than those of that form with up to 35 digits. - Michael S. Branicky, May 25 2021

Links

Table of n, a(n) for n=1..21.

Jonathan Wellons, Tables of Shared Digits [archived].

Example

23333524235^2 = 544453353225332335225.

Prog

(PARI) isokd(x) = (x < 2) || (x > 5);
isok(n) = !#select(x->isokd(x), digits(n)) && !#select(x->isokd(x), digits(n^2)); \\ Michel Marcus, Jul 02 2018
(Python) # uses auptod in A137110
print(auptod(16, only="2345")) # Michael S. Branicky, May 25 2021

Crossrefs

Cf. A137110.

Sequence in context: A249180 A135724 A137068 * A175977 A367673 A121270

Adjacent sequences: A137063 A137064 A137065 * A137067 A137068 A137069

Keyword

base,nonn

Author

Jonathan Wellons (wellons(AT)gmail.com), Jan 22 2008

Status

approved