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Search: id:A126867
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| A126867 |
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Largest even semiprime <= n^2. |
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+0
1
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| 4, 6, 14, 22, 34, 46, 62, 74, 94, 118, 142, 166, 194, 218, 254, 278, 314, 358, 398, 422, 482, 526, 566, 622, 674, 718, 778, 838, 898, 958, 1018, 1082, 1154, 1214, 1294, 1366, 1438, 1514, 1594, 1678, 1762, 1838, 1934, 2018, 2102, 2206, 2302, 2386, 2498, 2594
(list; graph; listen)
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OFFSET
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2,1
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FORMULA
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a(n)=max( A001358(i): A001358(i)<= A000290(n), A001358(i)= 0 mod 2). - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 17 2007
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MAPLE
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isA001358 := proc(n) if numtheory[bigomega](n)=2 then true; else false; fi; end: A126867 := proc(n) local a; a := n^2; while not isA001358(a) or a mod 2 <> 0 do a := a-1; od; RETURN(a); end: for n from 2 to 90 do printf("%d, ", A126867(n)); od; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 17 2007
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MATHEMATICA
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f[n_] := 2Prime[PrimePi[n^2/2]]; Table[f[n], {n, 2, 51}] (*Chandler*)
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CROSSREFS
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Sequence in context: A029647 A122555 A097271 this_sequence A027632 A084214 A030138
Adjacent sequences: A126864 A126865 A126866 this_sequence A126868 A126869 A126870
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KEYWORD
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easy,nonn
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AUTHOR
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Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Mar 16 2007
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Robert G. Wilson v and R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Mar 17 2007
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