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A103194 LAH transform of squares. 8
0, 1, 6, 39, 292, 2505, 24306, 263431, 3154824, 41368977, 589410910, 9064804551, 149641946796, 2638693215769, 49490245341642, 983607047803815, 20646947498718736, 456392479671188001, 10595402429677269174, 257723100178182605287, 6553958557721713088820 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

If the E.g.f. of b(n) is E(x) and a(n) = Sum{k=0..n} C(n,k)^2*(n-k)!*b(k), then the E.g.f. of a(n) is E(x/(1-x))/(1-x). - Vladeta Jovovic, Apr 16 2005

a(n) is the total number of elements in all partial permutations (injective partial functions) of {1,2,...,n} that are in a cycle.  A fixed point is considered to be in a cycle.  a(n) = Sum_{k=0..n} A206703(n,k)*k. - Geoffrey Critzer, Feb 11 2012.

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..200

P. Flajolet and R. Sedgewick, Analytic Combinatorics, Cambridge Univ. Press, 2009, page 132

N. J. A. Sloane, Transforms

FORMULA

a(n) = Sum_{k=0..n} n!/k!*binomial(n-1, k-1)*k^2.

E.g.f.: x/(1-x)^2*exp(x/ (1-x)).

Recurrence: (n-1)*a(n)-n*(2*n-1)*a(n-1)+n*(n-1)^2*a(n-2) = 0.

a(n) = n*A000262(n). - Vladeta Jovovic, Mar 20 2005

a(n) ~ n! * exp(-1/2+2*sqrt(n))*n^(1/4)/(2*sqrt(Pi)). - Vaclav Kotesovec, Aug 13 2013

a(n) = n!*hypergeom([2, 1-n], [1, 1], -1). - Peter Luschny, Mar 30 2015

MAPLE

with(combstruct): SetSeqSetL := [T, {T=Set(S), S=Sequence(U, card >= 1), U=Set(Z, card=1)}, labeled]: seq(k*count(SetSeqSetL, size=k), k=0..18); # Zerinvary Lajos, Jun 06 2007

a := n -> n!*hypergeom([2, 1-n], [1, 1], -1):

seq(simplify(a(n)), n=0..20); # Peter Luschny, Mar 30 2015

MATHEMATICA

nn = 20; a = 1/(1 - x); ay = 1/(1 - y x); D[Range[0, nn]! CoefficientList[ Series[Exp[a x] ay, {x, 0, nn}], x], y] /. y -> 1  (* Geoffrey Critzer, Feb 11 2012 *)

CROSSREFS

Cf. A001477.

Sequence in context: A253077 A231482 A122827 * A009018 A289996 A335344

Adjacent sequences:  A103191 A103192 A103193 * A103195 A103196 A103197

KEYWORD

easy,nonn

AUTHOR

Vladeta Jovovic, Mar 18 2005

STATUS

approved

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Last modified June 24 11:45 EDT 2021. Contains 345416 sequences. (Running on oeis4.)