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 A000197 a(n) = (n!)!. (Formerly M2187 N0874) 16
 1, 1, 2, 720, 620448401733239439360000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS The sequence 1, 2, 720!, 4!!!!, ... ,n!!...! (n times) grows too rapidly to have its own entry. See Hofstadter. a(n) is divisible by 2^A245087(n) but not by 2^(A245087(n)+1), A245087 being the number of trailing zeros in its binary expansion. Also, for n>1, the largest prime divisor of a(n) is the largest prime <= n!, which is listed in A006990(n). - Stanislav Sykora, Jul 14 2014 See b-file for a(5), which has 199 digits and is too large to include. - Jianing Song, Jun 28 2018 REFERENCES Archimedeans Problems Drive, Eureka, 37 (1974), 11. Douglas R. Hofstadter, Fluid concepts & creative analogies: computer models of the fundamental mechanisms of thought, Basic Books, 1995, pages 44-46. [From Colin Rowat, Sep 30 3011] N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Franklin T. Adams-Watters, Table of n, a(n) for n=0..5 R. Ondrejka, 1273 exact factorials, Math. Comp., 24 (1970), 231. Eric Weisstein's World of Mathematics, Factorial FORMULA a(n) = A000142(A000142(n)). - Wesley Ivan Hurt, Jul 14 2014 MAPLE A000197:=n->(n!)!: seq(A000197(n), n=0..5); # Wesley Ivan Hurt, Jul 14 2014 MATHEMATICA Table[(n!)!, {n, 0, 5}] (* Wesley Ivan Hurt, Jul 14 2014 *) PROG (MAGMA) [Factorial(Factorial(n)) : n in [0..5]]; // Wesley Ivan Hurt, Jul 14 2014 CROSSREFS Cf. A063979. - Robert G. Wilson v, Dec 04 2008 Cf. A152168. - Alois P. Heinz, Aug 04 2013 Cf. A000142, A006990, A245087. Sequence in context: A185667 A119781 A028367 * A036298 A153923 A167440 Adjacent sequences:  A000194 A000195 A000196 * A000198 A000199 A000200 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified December 9 09:20 EST 2019. Contains 329877 sequences. (Running on oeis4.)