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A121347
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Largest number whose factorial is less than (n!)^2.
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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; refs; listen; history; internal format)
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OFFSET
| 2,1
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EXAMPLE
| a(3)=4 because 4!=24 is the largest factorial not exceeding (3!)^2=36.
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PROG
| (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
| Cf. A121348 [difference between (n!)^2 and the next smaller factorial].
Sequence in context: A026351 A184656 A047212 * A106829 A190228 A083120
Adjacent sequences: A121344 A121345 A121346 * A121348 A121349 A121350
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KEYWORD
| nonn
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AUTHOR
| Hugo Pfoertner (hugo(AT)pfoertner.org), Aug 15 2006
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EXTENSIONS
| 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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