OFFSET
1,2
COMMENTS
Suggested by Example 2.24 in Lozansky and Rousseau. Hint: use Newton's equations.
REFERENCES
E. Lozansky and C. Rousseau, Winning Solutions, Springer, 1996; see p. 103.
FORMULA
E.g.f.: (1-exp(x/(x-1)))/(1-x)^2. - Vladeta Jovovic, May 03 2004
a(n) = n!*(n+1-LaguerreL(n,1,1)) = Sum_{k=1..n} (-1)^(k+1)*n!/k!*binomial(n+1,k+1). - Vladeta Jovovic, Apr 27 2006
a(n) = (3*n - 1)*a(n-1) - n*(3*n - 4)*a(n-2) + (n-2)*(n-1)*n*a(n-3). - Vaclav Kotesovec, Nov 13 2017
MATHEMATICA
Table[Sum[(-1)^(k+1)*n!/k!*Binomial[n+1, k+1], {k, 1, n}], {n, 1, 20}] (* Vaclav Kotesovec, Nov 13 2017 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, May 02 2004
EXTENSIONS
More terms from Vladeta Jovovic, May 03 2004
STATUS
approved