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Associated Stirling Number of the First Kind


The associated Stirling numbers of the first kind d_2(n,k)=d(n,k) are defined as the number of permutations of a given number n having exactly k permutation cycles, all of which are of length r=2 or greater (Comtet 1974, p. 256; Riordan 1980, p. 75). They are a special case of the more general numbers d_r(n,k), and have the recurrence relation

 d_2(n+1,k)=n[d_2(n,k)+d_2(n-1,k-1)]
(1)

with initial conditions d_2(n,k)=0 for n<=2k-1, and d_2(n,1)=(n-1)! (Appell 1880; Tricomi 1951; Carlitz 1958; Comtet 1974, pp. 256, 293, and 295). The generating function for d_2(n,k) is given by

 e^(-tu)(1-t)^(-u)=1+sum_(k=1)^(n/2)(d_2(n,k))/(n!)t^nu^k 
=1+((t^2)/2+(t^3)/3+(t^4)/4+(t^5)/5+(t^6)/6+...)u 
 +((t^4)/8+(t^5)/6+(13t^6)/(72)+...)u^2+((t^6)/(48)+...)u^3+...
(2)

(Comtet 1974, p. 256). The associated Stirling numbers of the first kind satisfy the sum identity

 sum_(k=1)^n(-1)^(k-1)d_2(n,k)=n-1.
(3)

For k>=2 and p a prime,

 d_2(p,k)=0 (mod p(p-1)).
(4)

For all integers l,

 sum_(m=1)^l(-1)^md_2(l+m,m)=(-1)^l,
(5)

and similarly,

 sum_(m=1)^l((-1)^md_2(l+m,m))/(l+m-1)=0
(6)

(Comtet 1974, p. 256).

Special cases of the associated Stirling numbers of the first kind are given by

d_2(n,1)=(n-1)!
(7)
d_2(2k,k)=(2k-1)!!
(8)
d_2(2k+1,k)=2/3k(2k+1)!!
(9)
d_2(2k+2,k)=((4k+5)(2k+2)!)/(18(k-1)!2^k)
(10)

(Comtet 1974, p. 256). The triangle of these numbers is given by

 1 
2 
6,3 
24,20 
120,130,15 
720,924,210 
5040,7308,2380,105
(11)

(OEIS A008306).


See also

Stirling Number of the First Kind

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References

Appell, P. "Développments en série entière de (1+ax)^(1/x)." Grunert Archiv 65, 171-175, 1880.Carlitz, L. "On Some Polynomials of Tricomi." Boll. Un. M. Ital. 13, 58-64, 1958.Carlitz, L. "Note on Nörlund's [sic] Polynomial B_n^((z))." Proc. Amer. Math. Soc. 11, 452-455, 1960.Comtet, L. Advanced Combinatorics: The Art of Finite and Infinite Expansions, rev. enl. ed. Dordrecht, Netherlands: Reidel, 1974.Riordan, J. An Introduction to Combinatorial Analysis. New York: Wiley, 1980.Sloane, N. J. A. Sequence A000457/M4736 in "The On-Line Encyclopedia of Integer Sequences."Tricomi, F. G. "A Class of Non-Orthogonal Polynomials Related to those of Laguerre." J. Analyse M. 1, 209-231, 1951.

Referenced on Wolfram|Alpha

Associated Stirling Number of the First Kind

Cite this as:

Weisstein, Eric W. "Associated Stirling Number of the First Kind." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/AssociatedStirlingNumberoftheFirstKind.html

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