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Search: id:A121347
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| A121347 |
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Largest number whose factorial is less than (n!)^2. |
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+0
3
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| 2, 4, 5, 7, 9, 10, 12, 14, 15, 17, 19, 20, 22, 24, 26, 27, 29, 31, 32, 34, 36, 38, 39, 41, 43, 44, 46, 48, 50, 51, 53, 55, 57, 58, 60, 62, 64, 65, 67, 69, 71, 72, 74, 76, 78, 79, 81, 83, 85, 87, 88, 90, 92, 94, 95, 97, 99, 101, 102, 104, 106, 108, 110, 111, 113, 115, 117, 118
(list; graph; listen)
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OFFSET
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2,1
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EXAMPLE
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a(3)=4 because 4!=24 is the largest factorial not exceeding (3!)^2=36.
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PROGRAM
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(PARI) A121347(n)= { local(lognf=2*sum(s=1, n, log(s)), k=1) ; while(1, if( sum(s=1, k, log(s))< lognf, k++, return(k-1) ; ) ; ) ; } { for(n=2, 80, print1(A121347(n), ", ") ; ) ; } - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 12 2007
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CROSSREFS
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Cf. A121348 [difference between (n!)^2 and the next smaller factorial].
Sequence in context: A004956 A026351 A047212 this_sequence A106829 A083120 A001614
Adjacent sequences: A121344 A121345 A121346 this_sequence A121348 A121349 A121350
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KEYWORD
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nonn
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AUTHOR
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Hugo Pfoertner (hugo(AT)pfoertner.org), Aug 15 2006
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EXTENSIONS
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a(2) corrected by Jon Schoenfield, Aug 27 2006
More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 12 2007
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