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 A131542 #24 Jul 20 2024 08:19:15
%S A131542 0,3,19,39,180,316,971,6836,25263,103825,279274,279268,1727604,
%T A131542 18053496,8760852,106892453
%N A131542 Exponent of least power of 2 having exactly n consecutive 8's in its decimal representation.
%H A131542 Popular Computing (Calabasas, CA), <a href="/A094776/a094776.jpg">Two Tables</a>, Vol. 1, (No. 9, Dec 1973), page PC9-16.
%e A131542 a(3)=39 because 2^39 (i.e., 549755813888) is the smallest power of 2 to contain a run of 3 consecutive eights in its decimal form.
%t A131542 a = ""; Do[ a = StringJoin[a, "8"]; b = StringJoin[a, "8"]; k = 1; While[ StringPosition[ ToString[2^k], a] == {} || StringPosition[ ToString[2^k], b] != {}, k++ ]; Print[k], {n, 1, 10} ]
%K A131542 more,nonn,base
%O A131542 0,2
%A A131542 _Shyam Sunder Gupta_, Aug 26 2007
%E A131542 Two more terms from _Sean A. Irvine_, May 31 2010
%E A131542 a(13)-a(14) from _Lars Blomberg_, Jan 24 2013
%E A131542 a(0)=0 prepended by and a(15) from _Paul Geneau de Lamarlière_, Jul 19 2024