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Search: id:A085986
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| A085986 |
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Square the square-free semiprimes. |
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+0
4
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| 36, 100, 196, 225, 441, 484, 676, 1089, 1156, 1225, 1444, 1521, 2116, 2601, 3025, 3249, 3364, 3844, 4225, 4761, 5476, 5929, 6724, 7225, 7396, 7569, 8281, 8649, 8836, 9025, 11236, 12321, 13225, 13924, 14161, 14884, 15129, 16641, 17689, 17956, 19881
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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A085986 is a member of a family of sequences directly related to A025487. first terms and known sequences are listed below: 1 A000007 2 A000040 4 A001248 6 A006881 8 A030078 12 A054753 16 A030514 24 A065036 30 A007304 32 A050997 36 this sequence 48 ? 60 ? 64 ? ...
Subset of A077448. The numbers in A077448 but not in here are 1, the squares of A046386, the squares of A067885 etc. [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 12 2008]
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FORMULA
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A085986(n) = A006881(n)^2
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EXAMPLE
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A006881 begins 6 10 14 15 ...
so A085986 begins 36 100 196 225 ...
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MATHEMATICA
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f[n_]:=FactorInteger[n][[1, 2]]==2&&Length[FactorInteger[n]]==2&&FactorInteger[n][[2, 2]]==2; lst={}; Do[If[f[n], AppendTo[lst, n]], {n, 4, 8!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Aug 14 2009]
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CROSSREFS
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Cf. A025487.
Sequence in context: A044604 A030627 A077448 this_sequence A027603 A163246 A014738
Adjacent sequences: A085983 A085984 A085985 this_sequence A085987 A085988 A085989
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KEYWORD
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easy,nonn
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AUTHOR
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Alford Arnold (Alford1940(AT)aol.com), Jul 06 2003
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