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 A067501 #13 Sep 17 2024 19:10:58 %S A067501 1,4,68719476736, %T A067501 95780971304118053647396689196894323976171195136475136, %U A067501 25108406941546723055343157692830665664409421777856138051584,1606938044258990275541962092341162602522202993782792835301376 %N A067501 Powers of 4 with digit sum also a power of 4. %C A067501 The next term (a(7)) has 915 digits. - _Harvey P. Dale_, Feb 12 2022 %t A067501 Select[4^Range[0,100],IntegerQ[Log[4,Total[IntegerDigits[#]]]]&] (* _Harvey P. Dale_, Feb 12 2022 *) %Y A067501 Cf. A067499, A067500. %K A067501 nonn,base %O A067501 1,2 %A A067501 _Amarnath Murthy_, Feb 11 2002 %E A067501 More terms from _Sascha Kurz_, Mar 18 2002 %E A067501 Offset changed by _Andrew Howroyd_, Sep 17 2024