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 A067469 #29 Jan 27 2021 05:34:44 %S A067469 1,8,11,18,21,28,31,38,41,48,51,58,61,68,71,81,91,101,104,111,114,121, %T A067469 124,131,134,141,144,151,154,161,164,171,174,184,194,197,204,207,214, %U A067469 217,224,227,234,237,244,247,254,257,264,267,277,287,297,300,307,310 %N A067469 Numbers k such that 2 is the first digit of 2^k. %C A067469 The asymptotic density of this sequence is log_10(3/2) = 0.176091... (A154580 - 1). - _Amiram Eldar_, Jan 27 2021 %H A067469 Muniru A Asiru, <a href="/A067469/b067469.txt">Table of n, a(n) for n = 1..5000</a> %t A067469 Select[Range@ 310, First@ IntegerDigits[2^#] == 2 &] (* _Michael De Vlieger_, Oct 15 2018 *) %o A067469 (PARI) is(n)=digits(2^n)[1]==2 \\ _Charles R Greathouse IV_, Jul 29 2013 %o A067469 (GAP) Filtered([1..310],n->ListOfDigits(2^n)[1]=2); # _Muniru A Asiru_, Oct 14 2018 %Y A067469 Cf. A067480, A154580. %K A067469 nonn,base %O A067469 1,2 %A A067469 _Benoit Cloitre_, Feb 22 2002