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 A377993 #9 Nov 22 2024 20:32:18
%S A377993 1,2,3,4,6,3,2,330,3,3
%N A377993 Number of integers whose arithmetic derivative (A003415) is equal to A024451(n), the arithmetic derivative of the n-th primorial.
%C A377993 a(n) is the number of natural numbers k such that k' = A003415(k) = A024451(n). The solutions k are listed in A377992.
%C A377993 For 1! = 1, there is an infinite number of integers k for which k' = 1 (all the primes), therefore the starting offset is 2.
%H A377993 <a href="/index/Pri#primorial_numbers">Index entries for sequences related to primorial numbers</a>
%F A377993 a(n) = A099302(A024451(n)).
%F A377993 a(n) = Sum_{k=1..A002620(A024451(n))} [A003415(k) = A024451(n)], where [ ] is the Iverson bracket.
%e A377993 There is just one number such that A003415(k) = A024451(2) = 5, and that is k=6, therefore a(2) = 1.
%e A377993 There are two numbers such that A003415(k) = A024451(3) = 31, and they are k=30 and k=58, therefore a(3) = 2.
%Y A377993 Row lengths of A377992.
%Y A377993 Cf. A002620, A003415, A024451, A099302.
%K A377993 nonn
%O A377993 2,2
%A A377993 _Antti Karttunen_, Nov 20 2024