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 A030701 #27 Feb 16 2025 08:32:35 %S A030701 0,1,2,3,4,7,8,9,12,14,16,17,18,36,38,43 %N A030701 Decimal expansion of 4^n contains no zeros (probably finite). %C A030701 Integers in A007377 / 2. Conjectured to be finite, and probably complete. - _M. F. Hasler_, Mar 08 2014 %H A030701 M. F. Hasler, <a href="https://oeis.org/wiki/Zeroless_powers">Zeroless powers</a>, OEIS Wiki, Mar 07 2014. %H A030701 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Zero.html">Zero</a>. %t A030701 Select[Range[0,50],DigitCount[4^#,10,0]==0&] (* _Paolo Xausa_, Oct 07 2023 *) %o A030701 (PARI) for(n=0, 99, vecmin(digits(4^n))&& print1(n", ")) \\ _M. F. Hasler_, Mar 07 2014 %o A030701 (Magma) [n: n in [0..500] | not 0 in Intseq(4^n)]; // _Vincenzo Librandi_, Mar 08 2014 %Y A030701 For the zeroless numbers (powers x^n), see A238938, A238939, A238940, A195948, A238936, A195908, A195946, A195945, A195942, A195943, A103662. %Y A030701 For the corresponding exponents, see A007377, A008839, A030700, A030701, A008839, A030702, A030703, A030704, A030705, A030706, A195944. %Y A030701 For other related sequences, see A052382, A027870, A102483, A103663. %K A030701 nonn,base %O A030701 1,3 %A A030701 _Eric W. Weisstein_ %E A030701 Offset corrected and initial 0 added by _M. F. Hasler_, Mar 07 2014