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 A064541 #27 Jun 02 2019 23:38:38 %S A064541 36,736,8736,48736,948736,2948736,32948736,432948736,3432948736, %T A064541 53432948736,353432948736,5353432948736,75353432948736, %U A064541 5075353432948736,15075353432948736,615075353432948736,8615075353432948736,98615075353432948736,8098615075353432948736,38098615075353432948736 %N A064541 Numbers k such that 2^k ends in k. %C A064541 There is no term with 15 digits. %H A064541 <a href="/index/Fi#final">Index entries for sequences related to final digits of numbers</a> %F A064541 a(n+1) is a suffix of 2^a(n) formed by a nonzero digit followed by a number of zeros and a(n). E.g., a(13)=75353432948736 and 2^a(13) ends with ...15075353432948736, hence a(14)=5075353432948736. - _Max Alekseyev_, Apr 18 2007 %F A064541 Can be obtained from A109405 by removing all repeats. - _Max Alekseyev_, May 11 2007 %e A064541 2^36 = 68719476736 which ends in 36. %t A064541 a[1] = 36; a[n_] := a[n] = For[ida = IntegerDigits[a[n-1]]; k = 1, True, k++, idk = IntegerDigits[k]; pm = PowerMod[2, an = FromDigits[Join[idk, ida]], 10^IntegerLength[an]]; If[pm == an, Return[an]]]; Array[a, 20] (* _Jean-François Alcover_, Feb 15 2018 *) %Y A064541 Cf. A121319, A109405, A206636. %Y A064541 The leading digits are listed in A064540. %Y A064541 Digits read backwards form A133612. %K A064541 base,nonn,nice %O A064541 1,1 %A A064541 Jonathan Ayres (jonathan.ayres(AT)btinternet.com), Oct 08 2001