A066275 Number of endofunctions of [n] such that some element is fixed, but 1 is not fixed.

0, 1, 10, 111, 1476, 23255, 425958, 8915263, 210156040, 5513215599, 159374246010, 5034663700847, 172583816090700, 6380915666604583, 253132868797656526, 10725414213389814015, 483431164831317069840

Offset

1,3

Links

Table of n, a(n) for n=1..17.

Formula

a(n) = n^n-n^(n-1)-(n-1)^n. E.g.f.: (T^3-T^2+T-x)/(T-T^2), where T=T(x) is Euler's tree function (see A000169).

Example

a(2)=1: [1->2,2->2].

Maple

A066275 := proc(n)
    n^n-n^(n-1)-(n-1)^n ;
end proc: # R. J. Mathar, Oct 31 2015

Crossrefs

Cf. A045531, A066274.

Sequence in context: A176736 A084031 A210507 * A362671 A344398 A046164

Adjacent sequences: A066272 A066273 A066274 * A066276 A066277 A066278

Keyword

nonn

Author

Len Smiley, Dec 09 2001

Status

approved