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 A086325 Let u(1)=0, u(2)=1, u(k)=u(k-1)+u(k-2)/(k-2); then a(n)=n!*u(n). (Formerly N0672) 2
 0, 2, 6, 36, 220, 1590, 12978, 118664, 1201464, 13349610, 161530270, 2114578092, 29780308116, 448995414686, 7215997736010, 123153028027920, 2224451568754288, 42395429898611154, 850263899633257014, 17900292623858042420, 394701452356069835340, 9096928711444657157382, 218739785834282892557026 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES F. N. David, M. G. Kendall and D. E. Barton, Symmetric Function and Allied Tables, Cambridge, 1966, p. 263, Table 7.5.1, row 3. J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 210, Table 3, Three-line Latin rectangles. N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..200 FORMULA a(n) = ceiling(n*n!/e) - (1-(-1)^n)/2. E.g.f.: x^2*exp(-x)/(1-x)^2. - Vladeta Jovovic, Nov 20 2003 a(n) = n*floor((n!+1)/e). [Gary Detlefs, Jul 13 2010] a(n) = n * A000166(n). [Joerg Arndt, Jul 09 2012] G.f.: x*f'(x), where f(x) = 1/(1 + x) + Sum_{k>=1} k^k*x^k/(1 + (k + 1)*x)^(k+1). - Ilya Gutkovskiy, Apr 13 2017 MAPLE a:=n->n!*add((-1)^k/k!, k=0..n): seq(a(n)*n, n=1..19); # Zerinvary Lajos, Dec 18 2007 with (combstruct):with (combinat):a:=proc(m) [ZL, {ZL=Set(Cycle(Z, card>=m))}, labeled]; end: ZLL:=a(2):seq(count(ZLL, size=n)*fibonacci(2, n), n=1..19); # Zerinvary Lajos, Jun 11 2008 with (combstruct):a:=proc(m) [ZL, {ZL=Set(Cycle(Z, card>=m))}, labeled]; end: ZLL:=a(2):seq(count(ZLL, size=n)*n, n=1..19); # Zerinvary Lajos, Jun 11 2008 MATHEMATICA Table[Subfactorial[n]*n, {n, 1, 19}] (* Zerinvary Lajos, Jul 09 2009 *) PROG (PARI) a(n) = n*((n! + 1)\exp(1)); \\ Indranil Ghosh, Apr 13 2017 CROSSREFS Cf. A000246, A000274, A000166. Sequence in context: A152668 A213918 A239889 * A074424 A002868 A002869 Adjacent sequences:  A086322 A086323 A086324 * A086326 A086327 A086328 KEYWORD nonn AUTHOR N. J. A. Sloane. This sequence appeared in the 1973 "Handbook", but was then omitted from the database. Resubmitted by Benoit Cloitre, Aug 30 2003. Entry revised by N. J. A. Sloane, Jun 11 2012 STATUS approved

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Last modified December 9 03:27 EST 2019. Contains 329872 sequences. (Running on oeis4.)