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 A341042 #13 Nov 12 2022 05:25:48
%S A341042 1,1,3,1,5,3,7,1,6,5,11,3,13,7,15,1,17,6,19,5,21,11,23,3,10,13,9,7,29,
%T A341042 15,31,1,33,17,35,6,37,19,39,5,41,21,43,11,30,23,47,3,14,10,51,13,53,
%U A341042 9,55,7,57,29,59,15,61,31,42,1,65,33,67,17,69,35,71,6,73,37,30
%N A341042 Multiplicative projection of odd part of n.
%H A341042 Amiram Eldar, <a href="/A341042/b341042.txt">Table of n, a(n) for n = 1..10000</a>
%H A341042 <a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a>.
%H A341042 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>.
%F A341042 a(n) = A000026(A000265(n)).
%F A341042 a(n) = A000026(n) if n odd, a(n) = a(n/2) if n even.
%F A341042 From _Amiram Eldar_, Nov 12 2022: (Start)
%F A341042 Multiplicative with a(2^e) = 1 and a(p^e) = e*p for p > 2.
%F A341042 Sum_{k=1..n} a(k) ~ c * n^2, where c = (6*zeta(2)^2/17) * Product_{p prime} (1 - 3/p^2 + 2/p^3 + 1/p^4 - 1/p^5) = 0.2947570019... . (End)
%e A341042 a(54) = a(2 * 3^3) = 3 * 3 = 9.
%p A341042 a:= n-> mul(`if`(i[1]=2, 1, i[1]*i[2]), i=ifactors(n)[2]):
%p A341042 seq(a(n), n=1..75); # _Alois P. Heinz_, Feb 03 2021
%t A341042 a[n_] := Times @@ (#[[1]] #[[2]] & /@ FactorInteger[n/2^IntegerExponent[n, 2]]); Table[a[n], {n, 75}]
%o A341042 (PARI) a(n) = {my(f = factor(n)); prod(i = 1, #f~, if(f[i,1]==2, 1, f[i,1] * f[i,2]));} \\ _Amiram Eldar_, Nov 12 2022
%Y A341042 Cf. A000026, A000079 (positions of 1's), A000265, A056911 (fixed points), A204455.
%K A341042 nonn,mult
%O A341042 1,3
%A A341042 _Ilya Gutkovskiy_, Feb 03 2021