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 A050734 #14 Oct 16 2019 03:34:36 %S A050734 1,4,16,64,256,1024,4096,16384,1048576,4194304,268435456,1073741824, %T A050734 4294967296,17179869184,68719476736,281474976710656,18014398509481984, %U A050734 72057594037927936,73786976294838206464,295147905179352825856,1208925819614629174706176,20282409603651670423947251286016,85070591730234615865843651857942052864 %N A050734 Numbers of form 4^k (values of k see A050725) containing no pair of consecutive equal digits (probably finite). %C A050734 No additional terms up to 4^25000. - _Harvey P. Dale_, Oct 06 2011 %t A050734 Select[4^Range[0,60],!MemberQ[Differences[IntegerDigits[#]],0]&] (* _Harvey P. Dale_, Oct 06 2011 *) %Y A050734 Cf. A043096, A050725. %K A050734 nonn,base %O A050734 1,2 %A A050734 _Patrick De Geest_, Sep 15 1999 %E A050734 Terms a(21), a(22), and a(23) added by _Harvey P. Dale_, Oct 06 2011