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 A378985 #8 Dec 13 2024 15:22:55
%S A378985 0,0,1,0,0,1,0,0,1,1,0,1,0,1,1,0,0,1,0,1,1,0,0,1,0,0,1,1,0,1,0,0,1,0,
%T A378985 1,1,0,0,1,1,0,1,0,1,1,0,0,1,0,1,1,1,0,1,0,1,1,0,0,2,0,0,1,0,0,1,0,0,
%U A378985 1,1,0,1,0,0,1,0,0,1,0,1,1,0,0,1,0,0,1,1,0,2,0,0,1,0,0,1,0,1,1,1,0,1,0,1,1,0,0,1,0,1,1,1,0,1,0,0,1,0,0,2
%N A378985 Number of iterations of x -> A003961(x) needed before the result is deficient, when starting from x = 2*n.
%C A378985 This grows slowly. See comments in A336835.
%H A378985 Antti Karttunen, <a href="/A378985/b378985.txt">Table of n, a(n) for n = 1..100000</a>
%H A378985 <a href="/index/Pri#prime_indices">Index entries for sequences related to prime indices in the factorization of n</a>.
%H A378985 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>.
%F A378985 a(n) = A336835(2*n).
%o A378985 (PARI)
%o A378985 A003961(n) = my(f = factor(n)); for (i=1, #f~, f[i, 1] = nextprime(f[i, 1]+1)); factorback(f); \\ From A003961
%o A378985 A336835(n) = { my(i=0); while(sigma(n) >= (n+n), i++; n = A003961(n)); (i); };
%o A378985 A378985(n) = A336835(2*n);
%Y A378985 Even bisection of A336835.
%Y A378985 Cf. A000203, A003961.
%Y A378985 Cf. arrays A341605, A378979.
%K A378985 nonn
%O A378985 1,60
%A A378985 _Antti Karttunen_, Dec 13 2024