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0, 0, 16, 162, 768, 2500, 6480, 14406, 28672, 52488, 90000, 146410, 228096, 342732, 499408, 708750, 983040, 1336336, 1784592, 2345778, 3040000, 3889620, 4919376, 6156502, 7630848, 9375000, 11424400, 13817466, 16595712, 19803868, 23490000, 27705630, 32505856
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OFFSET
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0,3
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COMMENTS
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For n>=1, a(n) is equal to the number of functions f:{1,2,3,4,5}->{1,2,...,n} such that for a fixed x in {1,2,3,4,5} and a fixed y in {1,2,...,n} we have f(x)<>y. - Aleksandar M. Janjic and Milan Janjic, Mar 13 2007
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LINKS
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Vincenzo Librandi, Table of n, a(n) for n = 0..10000
Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets
Index to sequences with linear recurrences with constant coefficients, signature (6,-15,20,-15,6,-1).
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FORMULA
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G.f.: 2*x^2*(x^3+18*x^2+33*x+8)/(x-1)^6. [Colin Barker, Nov 06 2012]
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MAPLE
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a:=n->sum(sum(n^3, j=1..n), k=2..n): seq(a(n), n=0..31); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 09 2007
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MATHEMATICA
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Table[n^5 - n^4, {n, 0, 40}] (* or *) LinearRecurrence[{6, -15, 20, -15, 6, -1}, {0, 0, 16, 162, 768, 2500}, 40] (* From Vladimir Joseph Stephan Orlovsky, Feb 20 2012 *)
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PROG
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(MAGMA) [n^5-n^4: n in [0..50]]; // Vincenzo Librandi, Feb 12 2012
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CROSSREFS
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Sequence in context: A000811 A041484 A011551 * A211558 A208311 A091363
Adjacent sequences: A085535 A085536 A085537 * A085539 A085540 A085541
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KEYWORD
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nonn,easy
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AUTHOR
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N. J. A. Sloane, Jul 05 2003
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STATUS
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approved
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