This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A158304 #14 Jan 02 2022 00:10:28 %S A158304 0,1,2,10,11,12,18,20,21,32,38,48,49,100,101,102,110,111,120,149,152, %T A158304 179,180,182,200,201,210,318,320,321,332,338,348,351,361,362,380,451, %U A158304 452,462,480,482,490,548,549,649,1000,1001,1002,1010,1011,1012,1020,1021 %N A158304 Numbers k such that k^2 contains no digit greater than 4. %H A158304 Harvey P. Dale, <a href="/A158304/b158304.txt">Table of n, a(n) for n = 1..1000</a> %H A158304 Erich Friedman, <a href="https://erich-friedman.github.io/numbers.html">What's Special About This Number?</a> %p A158304 A158304 := proc(n) option remember; if n= 1 then 0; else for a from procname(n-1)+1 do d := convert(convert(a^2,base,10),set) ; if max(op(d)) <= 4 then return a; end if; end do; end if; end proc: %p A158304 seq(A158304(n),n=1..100) ; # _R. J. Mathar_, May 23 2010 %t A158304 Select[Range[0,1100],Max[IntegerDigits[#^2]]<5&] (* _Harvey P. Dale_, Nov 06 2016 *) %Y A158304 Cf. A158082, A136810. %K A158304 nonn,base %O A158304 1,3 %A A158304 _N. J. A. Sloane_, May 23 2010 %E A158304 Extended by several correspondents, May 24 2010