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 A345005 #14 Jun 07 2021 06:50:32 %S A345005 81,3375,15625,231525,713097,1058841,1500625,4348377,5764801,16891497, %T A345005 163555875,209548647,239010993,239160735,254205875,267651475, %U A345005 405189675,451699875,958403475,1050284375,1213014231,1501534375,1695809375,1809323971,1942143291 %N A345005 Odd numbers whose arithmetic derivative (A003415) is equal to Dedekind psi (A001615) applied to the same number. %C A345005 Conjectured to be also the odd numbers k for which A344998(k) = A344999(k). %o A345005 (PARI) %o A345005 A001615(n) = if(1==n,n, my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[i, 2] + f[i, 1]^(f[i, 2]-1))); \\ After code in A001615 %o A345005 A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1])); %o A345005 isA345005(n) = ((n%2)&&(A003415(n)==A001615(n))); %Y A345005 Odd terms in A301939, but see also A345003. %Y A345005 Cf. A001615, A003415, A344998, A344999. %K A345005 nonn,more %O A345005 1,1 %A A345005 _Antti Karttunen_, Jun 05 2021