0,2

For n>=1, a(n+1) is equal to the number of functions f:{1,2,...,n+1}->{1,2,3,4,5,6,7} such that for fixed, different x_1, x_2,...,x_n in {1,2,...,n+1} and fixed y_1, y_2,...,y_n in {1,2,3,4,5,6,7} we have f(x_i)<>y_i, (i=1,2,...,n). - Milan R. Janjic (agnus(AT)blic.net), May 10 2007

Milan Janjic, Enumerative Formulas for Some Functions on Finite Sets

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 308

Index entries for sequences related to trees

a(n) = Sum_{ 0<=k<=n } A029653(n, k)*x^k for x = 5 . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Jul 10 2005

k := 7; if n = 0 then 1 else k*(k-1)^(n-1); fi;

with(finance):seq(floor(futurevalue(7, 5, n)), n=-1..18); # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Mar 25 2009]

Sequence in context: A102594 A053142 A094168 this_sequence A033133 A082035 A127016

Adjacent sequences: A003946 A003947 A003948 this_sequence A003950 A003951 A003952

nonn

N. J. A. Sloane (njas(AT)research.att.com).