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 A369745 #8 Jun 26 2024 21:57:13 %S A369745 0,0,0,2,0,7,0,4,6,11,0,12,0,15,19,8,0,17,0,18,26,21,0,22,15,25,12,26, %T A369745 0,39,0,12,37,31,41,29,0,35,44,36,0,55,0,38,38,41,0,36,28,38,55,44,0, %U A369745 39,58,46,62,49,0,69,0,53,52,22,69,79,0,56,73,80,0,49,0,61 %N A369745 a(n) = Sum_{p|n, p prime} p * pi(n/p). %F A369745 a(p^k) = p * pi(p^(k-1)), for p prime and k >= 1. - _Wesley Ivan Hurt_, Jun 26 2024 %t A369745 Table[DivisorSum[n, #*PrimePi[n/#] &, PrimeQ[#] &], {n, 100}] %Y A369745 Cf. A000720 (pi), A066328. %K A369745 nonn,easy %O A369745 1,4 %A A369745 _Wesley Ivan Hurt_, Jan 30 2024