%I A062119
%S A062119 0,2,12,72,480,3600,30240,282240,2903040,32659200,399168000,5269017600,
%T A062119 74724249600,1133317785600,18307441152000,313841848320000,
%U A062119 5690998849536000,108840352997376000,2189611807358976000
%N A062119 n! * (n-1).
%C A062119 For n>0 a(n) = number of permutations of length n+1 that have 2 predetermined 
               elements non-adjacent, e.g. for n=2, the permutations with say 1 
               and 2 non-adjacent are 132 and 231, therefore a(2)=2. - Jon Perry 
               (perry(AT)globalnet.co.uk), Jun 08 2003
%C A062119 Number of multiplications performed in a determinant. [From Mats O. Granvik 
               (mgranvik(AT)abo.fi), Sep 12 2008]
%H A062119 Harry J. Smith, <a href="b062119.txt">Table of n, a(n) for n=1,...,100</
               a>
%H A062119 Milan Janjic, <a href="http://www.pmfbl.org/janjic/">Enumerative Formulas 
               for Some Functions on Finite Sets</a>
%H A062119 S. R. Schmitt <a href="http://home.att.net/~srschmitt/script_determinant3.html">
               Determinants</a> [From Mats O. Granvik (mgranvik(AT)abo.fi), Sep 
               12 2008]
%p A062119 a:=n->sum(n!,j=2..n):seq(a(n), n=1..19); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Apr 30 2007
%p A062119 seq(sum(mul(j,j=1..n), k=2..n), n=1..19); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Jun 01 2007
%p A062119 a:=n->add((n!),j=1..n-1):seq(a(n), n=1..21); [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Aug 27 2008]
%p A062119 restart: G(x):=x^2/(1-x)^2: f[0]:=G(x): for n from 1 to 19 do f[n]:=diff(f[n-1],
               x) od: x:=0: seq(f[n],n=1..19);# [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Apr 01 2009]
%t A062119 a[n_]:=1*(n+2)!-2*(n+1)!; ..and/or.. a[n_]:=n!*(n-1); [From Vladimir 
               Orlovsky (4vladimir(AT)gmail.com), Dec 05 2008]
%t A062119 Table[Sum[n!, {i, 2, n}], {n, 1, 19}] [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), 
               Jul 12 2009]
%o A062119 (PARI) { f=1; for (n=1, 100, f*=n; write("b062119.txt", n, " ", f*(n 
               - 1)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Aug 02 
               2009]
%Y A062119 Cf. A018931.
%Y A062119 a(n)=2*A001286(n). Cf. A052849.
%Y A062119 A001563 [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Aug 27 2008]
%Y A062119 Sequence in context: A119921 A167747 A018931 this_sequence A052556 A052833 
               A144086
%Y A062119 Adjacent sequences: A062116 A062117 A062118 this_sequence A062120 A062121 
               A062122
%K A062119 easy,nonn
%O A062119 1,2
%A A062119 Olivier Gerard (olivier.gerard(AT)gmail.com), Jun 13 2001
%E A062119 Last term a(19) corrected by Harry J. Smith (hjsmithh(AT)sbcglobal.net), 
               Aug 02 2009