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 A329878 Numbers k such that k and psi(k) have the same set of prime divisors, where psi is the Dedekind psi function (A001615). 1
 1, 6, 12, 18, 24, 36, 48, 54, 72, 96, 108, 144, 150, 162, 192, 216, 288, 294, 300, 324, 384, 432, 450, 486, 576, 588, 600, 648, 726, 750, 768, 864, 882, 900, 972, 1152, 1176, 1200, 1296, 1350, 1452, 1458, 1500, 1536, 1728, 1734, 1764, 1800, 1944, 2058, 2178 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Numbers k such that rad(psi(k)) = rad(k), where rad(k) is the squarefree kernel of k (A007947). LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 EXAMPLE 6 is in the sequence since 6 = 2 * 3 and psi(6) = 12 = 2^2 * 3 have the same set of prime divisors, {2, 3}. MATHEMATICA rad[n_] := Times @@ (First@# & /@ FactorInteger@ n); psi[1] = 1; psi[n_] := n * Times @@ (1 + 1/Transpose[FactorInteger[n]][[1]]); Select[Range[2000], rad[psi[#]] == rad[#] &] CROSSREFS Cf. A001615, A007947, A027598, A055744. Sequence in context: A358757 A353530 A244193 * A215142 A033845 A187778 Adjacent sequences: A329875 A329876 A329877 * A329879 A329880 A329881 KEYWORD nonn AUTHOR Amiram Eldar, Nov 23 2019 STATUS approved

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Last modified August 14 12:13 EDT 2024. Contains 375164 sequences. (Running on oeis4.)