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 A339809 #7 Dec 19 2020 05:47:25
%S A339809 0,1,2,5,4,9,14,29,6,13,20,41,34,69,104,209,10,21,32,65,54,109,164,
%T A339809 329,76,153,230,461,384,769,1154,2309,12,25,38,77,64,129,194,389,90,
%U A339809 181,272,545,454,909,1364,2729,142,285,428,857,714,1429,2144,4289,1000,2001,3002,6005,5004,10009,15014,30029,16,33,50
%N A339809 a(n) = A019565(n) - 1.
%H A339809 Antti Karttunen, <a href="/A339809/b339809.txt">Table of n, a(n) for n = 0..8192</a>
%o A339809 (PARI)
%o A339809 A019565(n) = { my(m=1, p=1); while(n>0, p = nextprime(1+p); if(n%2, m *= p); n >>= 1); (m); };
%o A339809 A339809(n) = (A019565(n)-1);
%Y A339809 Cf. A019565, A339810, A339811, A339812.
%Y A339809 Cf. also A339820, A339821.
%K A339809 nonn
%O A339809 0,3
%A A339809 _Antti Karttunen_, Dec 18 2020