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 A067489 #10 Oct 22 2018 11:51:32 %S A067489 1,19683,177147,1594323,14348907,129140163,1162261467,10460353203, %T A067489 1853020188851841,16677181699666569,150094635296999121, %U A067489 1350851717672992089,12157665459056928801,109418989131512359209 %N A067489 Powers of 3 with initial digit 1. %H A067489 Muniru A Asiru, <a href="/A067489/b067489.txt">Table of n, a(n) for n = 1..625</a> %t A067489 Select[3^Range[0,5*10^6],First[IntegerDigits[#]]==1&] (* _Harvey P. Dale_, Oct 09 2015 *) %o A067489 (GAP) Filtered(List([0..50],n->3^n),i->ListOfDigits(i)[1]=1); # _Muniru A Asiru_, Oct 22 2018 %Y A067489 Cf. A067480, A067481, A067482, A067483, A067484, A067485, A067486, A067487, A067488. %K A067489 base,easy,nonn %O A067489 1,2 %A A067489 _Amarnath Murthy_, Feb 09 2002 %E A067489 Offset 1 from _Michel Marcus_, Oct 19 2018