The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A137066 Numbers k such that k and k^2 use only the digits 2, 3, 4 and 5. 1

%I #23 Jul 05 2021 11:21:35

%S 2,5,235,2335,23335,233335,2333335,2354235,23333335,233333335,

%T 2333333335,2333524235,23333333335,23333524235,233333333335,

%U 2333333333335,23333333333335,233333333333335,2333333333333335,23333333333333335,233333333333333335

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

%C Generated with DrScheme.

%C 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

%C There are no others than those of that form with up to 35 digits. - _Michael S. Branicky_, May 25 2021

%H Jonathan Wellons, <a href="http://jonathanwellons.com/shared-digits/">Tables of Shared Digits</a>

%e 23333524235^2 = 544453353225332335225.

%o (PARI) isokd(x) = (x < 2) || (x > 5);

%o isok(n) = !#select(x->isokd(x), digits(n)) && !#select(x->isokd(x), digits(n^2)); \\ _Michel Marcus_, Jul 02 2018

%o (Python) # uses auptod in A137110

%o print(auptod(16, only="2345")) # _Michael S. Branicky_, May 25 2021

%Y Cf. A137110.

%K base,nonn

%O 1,1

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 9 13:48 EST 2023. Contains 367691 sequences. (Running on oeis4.)