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 A320865 #12 Nov 21 2018 12:23:55 %S A320865 9007199254740992,9223372036854775808,9444732965739290427392, %T A320865 9671406556917033397649408,9903520314283042199192993792, %U A320865 91343852333181432387730302044767688728495783936,93536104789177786765035829293842113257979682750464 %N A320865 Powers of 2 with initial digit 9. %H A320865 Muniru A Asiru, <a href="/A320865/b320865.txt">Table of n, a(n) for n = 1..150</a> %H A320865 <a href="/index/Di#divseq">Index to divisibility sequences</a> %p A320865 select(x->"9"=""||x[1],[2^n$n=0..200])[]; %t A320865 Select[2^Range[200], IntegerDigits[#][[1]] == 9 &] (* _Amiram Eldar_, Nov 21 2018 *) %o A320865 (GAP) Filtered(List([0..200],n->2^n),i->ListOfDigits(i)[1]=9); %o A320865 (PARI) select(x->(digits(x)[1]==9), vector(200, n, 2^n)) \\ _Michel Marcus_, Nov 21 2018 %Y A320865 Cf. A000079 (powers of 2), A008952 (leading digit of 2^n), A217402 (numbers starting with 9). %Y A320865 Powers of 2 with initial digit k, (k = 1..9): A067488, A067480, A320859, A320860, A320861, A320862, A320863, A320864, this sequence. %K A320865 base,nonn %O A320865 1,1 %A A320865 _Muniru A Asiru_, Nov 21 2018