cp's OEIS Frontend

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.

A358223 Inverse Möbius transform of A181819, prime shadow function.

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%I A358223 #15 Oct 23 2023 02:02:17
%S A358223 1,3,3,6,3,9,3,11,6,9,3,18,3,9,9,18,3,18,3,18,9,9,3,33,6,9,11,18,3,27,
%T A358223 3,29,9,9,9,36,3,9,9,33,3,27,3,18,18,9,3,54,6,18,9,18,3,33,9,33,9,9,3,
%U A358223 54,3,9,18,42,9,27,3,18,9,27,3,66,3,9,18,18,9,27,3,54,18,9,3,54,9,9,9,33,3,54
%N A358223 Inverse Möbius transform of A181819, prime shadow function.
%C A358223 Multiplicative and dependent only on the prime signature (A046523) because also A181819 is.
%H A358223 Michael De Vlieger, <a href="/A358223/b358223.txt">Table of n, a(n) for n = 1..16384</a>
%H A358223 <a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a>.
%F A358223 a(n) = Sum_{d|n} A181819(d).
%F A358223 Multiplicative with a(p^e) = 1 + Sum_{k=1..e} prime(k) = A014284(e+1). - _Amiram Eldar_, Oct 23 2023
%t A358223 f[n_] := f[n] = Times @@ Prime@ FactorInteger[n][[All, -1]]; Array[DivisorSum[#, f] - 1 &, 90] (* _Michael De Vlieger_, Nov 30 2022 *)
%o A358223 (PARI)
%o A358223 A181819(n) = factorback(apply(e->prime(e),(factor(n)[,2])));
%o A358223 A358223(n) = sumdiv(n,d,A181819(d));
%Y A358223 Cf. A014284, A046523, A181819.
%K A358223 nonn,mult
%O A358223 1,2
%A A358223 _Antti Karttunen_, Nov 30 2022