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 A382352 #9 Mar 29 2025 18:56:54
%S A382352 1,2,4,8,16,32,64,128,195,256,390,512,585,780,975,1024,1170,1560,1755,
%T A382352 1950,2048,2340,2535,2925,3120,3510,3900,4096,4680,4875,5070,5265,
%U A382352 5850,6240,7020,7605,7800,8192,8775,9360,9750,10101,10140,10530,11700,12480,12675,14040,14625
%N A382352 Numbers k such that the sum of the reciprocals of the indices of distinct prime factors of k is an integer.
%H A382352 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>.
%t A382352 Join[{1}, Select[Range[2, 15000], IntegerQ[Plus @@ (1/PrimePi[#[[1]]] & /@ FactorInteger[#])] &]]
%o A382352 (PARI) isok(k) = my(f=factor(k)); denominator(sum(i=1, #f~, 1/primepi(f[i,1]))) == 1; \\ _Michel Marcus_, Mar 22 2025
%Y A382352 Cf. A072873, A316856.
%K A382352 nonn
%O A382352 1,2
%A A382352 _Ilya Gutkovskiy_, Mar 22 2025