OFFSET
1,2
COMMENTS
For n>1, equals (-1)^(n+1) * BarnesG(n+2) times the determinant of the n X n matrix whose (i,j)-entry equals (i!-1)/i! if i=j and equals 1 otherwise. - John M. Campbell, Sep 14 2011
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..100
FORMULA
Let u(1)=1, u(2)=0 and u(k)=u(k-1)-1/k*u(k-2) then for n>2 a(n-1)=-u(n)*n!. - Benoit Cloitre, Nov 05 2004
a(1)=1 and, for n>=2, a(n) = sum(k=2..n, k!). - Robert G. Wilson v, Nov 12 2004
Conjecture: a(n) - (n+1)*a(n-1) + n*a(n-2) = 0. - R. J. Mathar, Jun 13 2013
G.f.: 1 - 1/(1-x) + W(0)/(1-x), where W(k) = 1 - x*(k+2)/( x*(k+2) - 1/(1 - x*(k+1)/( x*(k+1) - 1/W(k+1) ))); (continued fraction). - Sergei N. Gladkovskii, Aug 25 2013
MAPLE
a[1]:=1; a[2]:=2; for n from 3 to 20 do a[n]:=a[n-1]+factorial(n) end do; # Francesco Daddi, Aug 03 2011
MATHEMATICA
Table[Sum[k!, {k, n}] - 1, {n, 2, 20}] (* Robert G. Wilson v, Nov 12 2004 *)
PROG
(PARI) u1=1; u2=0; z=-1; for(n=3, 100, u3=u2+z/n*u1; u1=u2; u2=u3; if(n>0, print1(-(u3)*n!, ", "))) \\ Benoit Cloitre
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
More terms from Robert G. Wilson v, Nov 12 2004
STATUS
approved