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 A082293 Numbers having exactly one square divisor > 1. 10
 4, 8, 9, 12, 18, 20, 24, 25, 27, 28, 40, 44, 45, 49, 50, 52, 54, 56, 60, 63, 68, 75, 76, 84, 88, 90, 92, 98, 99, 104, 116, 117, 120, 121, 124, 125, 126, 132, 135, 136, 140, 147, 148, 150, 152, 153, 156, 164, 168, 169, 171, 172, 175, 184, 188, 189, 198, 204, 207, 212 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers of the form m*p^2, p prime and m squarefree (A005117). [Corrected by Peter Munn, Nov 17 2020] The asymptotic density of this sequence is (6/Pi^2)*Sum_{n>=1} 1/prime(n)^2 = 0.274933... (A222056). - Amiram Eldar, Jul 07 2020 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 FORMULA A046951(a(n)) = 2. MATHEMATICA Select[Range[2, 200], MemberQ[{2, 3}, (e = Sort[FactorInteger[#][[;; , 2]]])[[-1]]] && (Length[e] == 1 || e[[-2]] == 1) &] (* Amiram Eldar, Jul 07 2020 *) PROG (PARI) is(n)=my(f=vecsort(factor(n)[, 2], , 4)); #f && f[1]>1 && f[1]<4 && (#f==1 || f[2]==1) \\ Charles R Greathouse IV, Oct 16 2015 CROSSREFS Cf. A005117, A046951, A222056. Complement of A048111 within A013929. Subsequence of A252849. Disjoint union of A048109 and A060687. A285508 is a subsequence. Sequence in context: A370076 A252849 A375229 * A374593 A048944 A211658 Adjacent sequences: A082290 A082291 A082292 * A082294 A082295 A082296 KEYWORD nonn AUTHOR Reinhard Zumkeller, Apr 08 2003 STATUS approved

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Last modified September 15 08:55 EDT 2024. Contains 375932 sequences. (Running on oeis4.)