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 A339905 #10 Dec 08 2022 07:37:05
%S A339905 1,2,4,4,6,8,10,8,16,12,12,16,16,20,24,16,18,32,22,24,40,24,28,32,36,
%T A339905 32,64,40,30,48,36,32,48,36,60,64,40,44,64,48,42,80,46,48,96,56,52,64,
%U A339905 100,72,72,64,58,128,72,80,88,60,60,96,66,72,160,64,96,96,70,72,112,120,72,128,78,80,144,88,120,128,82
%N A339905 Fully multiplicative with a(prime(k)) = prime(k+1) - 1.
%H A339905 Antti Karttunen, <a href="/A339905/b339905.txt">Table of n, a(n) for n = 1..10205</a>
%H A339905 Antti Karttunen, <a href="/A339905/a339905.txt">Data supplement: n, a(n) computed for n = 1..65537</a>
%F A339905 a(n) = A003958(A003961(n)).
%F A339905 Sum_{k=1..n} a(k) ~ c * n^2, where c = (1/2) * Product_{p prime} ((p^2-p)/(p^2-nextprime(p)+1)) = 0.73732173..., where nextprime is A151800. - _Amiram Eldar_, Dec 08 2022
%o A339905 (PARI) A339905(n) = if(1==n,n,my(f=factor(n)); for(i=1,#f~,f[i,1] = nextprime(1+f[i,1])-1); factorback(f));
%Y A339905 Cf. A003958, A003961, A151800, A339903 (the odd part).
%Y A339905 Coincides with A003972 on A005117.
%K A339905 nonn,mult
%O A339905 1,2
%A A339905 _Antti Karttunen_, Dec 30 2020