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 A099888 #8 May 09 2023 18:30:00
%S A099888 1,2,8,16,80,160,640,2784,6560,21824,65280,131072,524800,1056192,
%T A099888 4201728,8408000,43046720,86135424,361186816,1467183104,3443838080,
%U A099888 11367226112,32550397696,70111011712,282403304960,569106797952
%N A099888 XOR BINOMIAL transform of the powers of 3.
%C A099888 The diagonal of the XOR difference triangle A099887. The XOR BINOMIAL transform of this sequence returns the powers of 3. See A099884 for the definitions of the XOR BINOMIAL transform and the XOR difference triangle.
%H A099888 Paul D. Hanna, <a href="/A099888/b099888.txt">Table of n, a(n) for n = 0..1024</a>
%F A099888 a(n) = SumXOR_{k=0..n} (C(n, k) mod 2)*3^k, where SumXOR is summation under XOR.
%o A099888 (PARI) a(n)=local(B);B=0;for(i=0,n,B=bitxor(B,binomial(n,i)%2*3^(n-i)));B
%Y A099888 Cf. A099884, A099887.
%K A099888 nonn
%O A099888 0,2
%A A099888 _Paul D. Hanna_, Oct 29 2004