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A001785
Second-order reciprocal Stirling number (Fekete) a(n) = [[2n+4, n]]. The number of n-orbit permutations of a (2n+4)-set with at least 2 elements in each orbit. Also known as associated Stirling numbers of the first kind (e.g., Comtet).
(Formerly M5382 N2338)
3
1, 120, 7308, 303660, 11098780, 389449060, 13642629000, 486591585480, 17856935296200, 678103775949600, 26726282654771700, 1094862336960892500, 46641683693715610500, 2066075391660447667500, 95122549872697437090000
OFFSET
0,2
REFERENCES
L. Comtet, Advanced Combinatorics, Reidel, 1974, p. 256.
C. Jordan, Calculus of Finite Differences. Budapest, 1939, p. 152.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
A. E. Fekete, Apropos two notes on notation, Amer. Math. Monthly, 101 (1994), 771-778.
H. W. Gould, Harris Kwong, and Jocelyn Quaintance, On Certain Sums of Stirling Numbers with Binomial Coefficients, J. Integer Sequences, 18 (2015), #15.9.6.
C. Jordan, On Stirling's Numbers, Tohoku Math. J., 37 (1933), 254-278.
FORMULA
a(n) = [[2n+4, n]] = Sum_{i=0..n} (-1)^i*binomial(2n+4, 2n+4-i)*[2n+4-i, n-i] where [n, k] is the unsigned Stirling number of the first kind. - Barbara Haas Margolius (margolius(AT)math.csuohio.edu), Dec 14 2000
Recurrence: 30*(n-1)*(116*n+75)*a(n) + (-6960*n^3-49760*n^2-112691*n-80787)*a(n-1) + (n+1)*(2*n+1)*(20*n+21)*a(n-2) = 0. - R. J. Mathar, Jul 18 2015
For n>0, a(n) = (1113 + 1447*n + 600*n^2 + 80*n^3)*(2*n+4)!/(1215*2^(n+3)*(n-1)!). - Vaclav Kotesovec, Jan 17 2016
Recurrence (for n>1): (n-1)*(80*n^3 + 360*n^2 + 487*n + 186)*a(n) = (n+2)*(2*n+3)*(80*n^3 + 600*n^2 + 1447*n + 1113)*a(n-1). - Vaclav Kotesovec, Jan 18 2016
MAPLE
with(combinat):s1 := (n, k)->sum((-1)^i*binomial(n, i)*abs(stirling1(n-i, k-i)), i=0..n); for j from 1 to 20 do s1(2*j+4, j); od; # Barbara Haas Margolius (margolius(AT)math.csuohio.edu), Dec 14 2000
MATHEMATICA
Prepend[Table[Sum[(-1)^i Binomial[2 n + 4, 2 n + 4 - i] Abs@ StirlingS1[2 n + 4 - i, n - i], {i, 0, n}], {n, 14}] , 1] (* Michael De Vlieger, Jan 04 2016 *)
PROG
(PARI) a(n) = if (!n, 1, sum(i=0, n, (-1)^i*binomial(2*n+4, 2*n+4-i)*abs(stirling(2*n+4-i, n-i, 1)))); \\ Michel Marcus, Jan 04 2016
(Magma) [1] cat [(1113+1447*n+600*n^2+80*n^3)*Factorial(2*n+4)/(1215*2^(n+ 3)*Factorial(n-1)): n in [1..15]]; // Vincenzo Librandi, Jan 18 2016
CROSSREFS
KEYWORD
nonn
EXTENSIONS
More terms from Barbara Haas Margolius (margolius(AT)math.csuohio.edu), Dec 14 2000
Offset changed to 0 by Michel Marcus, Jan 04 2016
STATUS
approved