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 A080408 #20 Jul 28 2022 09:06:41 %S A080408 2,3,6,14,35,116,448,1980,10098,57840,368201,2578384,19697486, %T A080408 163017000,1452918806,13874348700,141322966623,1529472867448, %U A080408 17526468199148,211996227034964,2699219798770446,36085910558435148,505406091697374877 %N A080408 Boustrophedon transform of the continued fraction of e (A003417). %H A080408 J. Millar, N. J. A. Sloane and N. E. Young, A new operation on sequences: the Boustrophedon transform, J.Combin. Theory, 17A (1996) 44-54 (<a href="http://neilsloane.com/doc/bous.txt">Abstract</a>, <a href="http://neilsloane.com/doc/bous.pdf">pdf</a>, <a href="http://neilsloane.com/doc/bous.ps">ps</a>). %H A080408 N. J. A. Sloane, <a href="/transforms.txt">Transforms</a> %H A080408 <a href="/index/Bo#boustrophedon">Index entries for sequences related to boustrophedon transform</a> %F A080408 a(n) appears to be asymptotic to C*n!*(2/Pi)^n where C = 9.27921365277635263761227970562207183019110298580498662908878310... - _Benoit Cloitre_ and Mark Hudson (mrmarkhudson(AT)hotmail.com) %e A080408 We simply apply the Boustrophedon transform to [2,1,2,1,1,4,1,1,6,1,1,8,1,1,...] %o A080408 (Python) %o A080408 from itertools import count, islice, accumulate %o A080408 def A080408_gen(): # generator of terms %o A080408 blist = tuple() %o A080408 for n in count(1): %o A080408 yield (blist := tuple(accumulate(reversed(blist),initial=2 if n == 1 else 1 if n % 3 else n//3<<1)))[-1] %o A080408 A080408_list = list(islice(A080408_gen(),25)) # _Chai Wah Wu_, Jul 27 2022 %Y A080408 Cf. A003417, A001113, A080406, A080407. %K A080408 nonn,easy %O A080408 0,1 %A A080408 Mark Hudson (mrmarkhudson(AT)hotmail.com), Feb 17 2003