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 A019466 #18 Oct 24 2024 15:28:44
%S A019466 3,3,4,8,10,30,33,132,136,680,685,4110,4116,28812,28819,230552,230560,
%T A019466 2075040,2075049,20750490,20750500,228255500,228255511,2739066132,
%U A019466 2739066144,35607859872,35607859885,498510038390,498510038404,7477650576060,7477650576075,119642409217200
%N A019466 Multiply by 1, add 1, multiply by 2, add 2, etc.; start with 3.
%H A019466 Paolo Xausa, <a href="/A019466/b019466.txt">Table of n, a(n) for n = 0..800</a>
%t A019466 Module[{a = 3}, Join[{a}, Flatten[Array[{a *= #, a += #} &, 20]]]] (* _Paolo Xausa_, Oct 24 2024 *)
%o A019466 (PARI) A019466(n,a=3)={for(i=2,n+1,if(bittest(i,0),a+=i\2,a*=i\2));a} \\ _M. F. Hasler_, Feb 25 2018
%Y A019466 Cf. A082458 (same, but start with 0), A019464 (start with 1), A019465 (start with 2).
%Y A019466 Cf. A019460 .. A019463 & A082448 (similar, but first add, then multiply).
%K A019466 nonn
%O A019466 0,1
%A A019466 _N. J. A. Sloane_
%E A019466 Edited by _M. F. Hasler_, Feb 25 2018