Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #10 Jan 18 2024 18:13:10
%S 0,0,0,0,0,0,1,1,0,0,2,9,18
%N a(n) is the number of integers, not semiprimes, whose arithmetic derivative is equal to the n-th primorial.
%C a(n) = number of solutions k to equation A003415(k) = A002110(n) with A001222(k) > 2.
%H Antti Karttunen, <a href="/A369000/a369000.txt">PARI-program</a>
%H <a href="/index/Pri#primorial_numbers">Index entries for sequences related to primorial numbers</a>
%F a(n) = A351029(n) - A116979(n).
%o (PARI) \\ See the attached PARI-program.
%Y Cf. A001222, A002110, A003415, A116979, A351029, A366890 (solutions themselves).
%K nonn,hard,more
%O 1,11
%A _Antti Karttunen_, Jan 16 2024