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 A060281 Triangle T(n,k) read by rows giving number of labeled mappings (or functional digraphs) from n points to themselves (endofunctions) with k cycles, k=1..n. 20
 1, 3, 1, 17, 9, 1, 142, 95, 18, 1, 1569, 1220, 305, 30, 1, 21576, 18694, 5595, 745, 45, 1, 355081, 334369, 113974, 18515, 1540, 63, 1, 6805296, 6852460, 2581964, 484729, 49840, 2842, 84, 1, 148869153, 158479488, 64727522, 13591116, 1632099, 116172, 4830, 108, 1 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Also called sagittal graphs. T(n,k)=1 iff n=k (counts the identity mapping of [n]). - Len Smiley, Apr 03 2006 Also the coefficients of the tree polynomials t_{n}(y) defined by (1-T(z))^(-y) = Sum_{n>=0} t_{n}(y) (z^n/n!) where T(z) is Cayley's tree function T(z) = Sum_{n>=1} n^(n-1) (z^n/n!) giving the number of labeled trees A000169. - Peter Luschny, Mar 03 2009 REFERENCES I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983. W. Szpankowski. Average case analysis of algorithms on sequences. John Wiley & Sons, 2001. - Peter Luschny, Mar 03 2009 LINKS Alois P. Heinz, Rows n = 1..141, flattened Julia Handl and Joshua Knowles, An Investigation of Representations and Operators for Evolutionary Data Clustering with a Variable Number of Clusters, in Parallel Problem Solving from Nature-PPSN IX, Lecture Notes in Computer Science, Volume 4193/2006, Springer-Verlag. [From N. J. A. Sloane, Jul 09 2009] D. E. Knuth, Convolution polynomials, The Mathematica J., 2 (1992), 67-78. D. E. Knuth and B. Pittel, A recurrence related to trees, Proceedings of the American Mathematical Society, 105(2):335-349, 1989. [From Peter Luschny, Mar 03 2009] J. Riordan, Enumeration of Linear Graphs for Mappings of Finite Sets, Ann. Math. Stat., 33, No. 1, Mar. 1962, pp. 178-185. David M. Smith, Geoffrey Smith, Tight Bounds on Information Leakage from Repeated Independent Runs, 2017 IEEE 30th Computer Security Foundations Symposium (CSF). FORMULA E.g.f.: 1/(1 + LambertW(-x))^y. T(n,k) = Sum_{j=0..n-1} C(n-1,j)*n^(n-1-j)*(-1)^(k+j+1)*A008275(j+1,k) = Sum_{j=0..n-1} binomial(n-1,j)*n^(n-1-j)*s(j+1,k). [Riordan] (Note: s(m,p) denotes signless Stirling cycle number (first kind), A008275 is the signed triangle.) - Len Smiley, Apr 03 2006 EXAMPLE Triangle T(n,k) begins: :       1; :       3,       1; :      17,       9,       1; :     142,      95,      18,      1; :    1569,    1220,     305,     30,     1; :   21576,   18694,    5595,    745,    45,    1; :  355081,  334369,  113974,  18515,  1540,   63,  1; : 6805296, 6852460, 2581964, 484729, 49840, 2842, 84, 1; : ... T(3,2)=9: (1,2,3)--> [(2,1,3),(3,2,1),(1,3,2),(1,1,3),(1,2,1), (1,2,2),(2,2,3),(3,2,3),(1,3,3)]. From Peter Luschny, Mar 03 2009: (Start) Tree polynomials (with offset 0): t_0(y) = 1; t_1(y) = y; t_2(y) = 3y + y^2; t_3(y) = 17y + 9y^2 + y^3; (End) MAPLE with(combinat):T:=array(1..8, 1..8):for m from 1 to 8 do for p from 1 to m do T[m, p]:=sum(binomial(m-1, k)*m^(m-1-k)*(-1)^(p+k+1)*stirling1(k+1, p), k=0..m-1); print(T[m, p]) od od; # Len Smiley, Apr 03 2006 From Peter Luschny, Mar 03 2009: (Start) T := z -> sum(n^(n-1)*z^n/n!, n=1..16): p := convert(simplify(series((1-T(z))^(-y), z, 12)), 'polynom'): seq(print(coeff(p, z, i)*i!), i=0..8); (End) MATHEMATICA t=Sum[n^(n-1) x^n/n!, {n, 1, 10}]; Transpose[Table[Rest[Range[0, 10]! CoefficientList[Series[Log[1/(1 - t)]^n/n!, {x, 0, 10}], x]], {n, 1, 10}]]//Grid (* Geoffrey Critzer, Mar 13 2011*) Table[k! SeriesCoefficient[1/(1 + ProductLog[-t])^x, {t, 0, k}, {x, 0, j}], {k, 10}, {j, k}] (* Jan Mangaldan, Mar 02 2013 *) CROSSREFS Row sums: A000312. Columns k=1-10 give: A001865, A065456, A273434, A273435, A273436, A273437, A273438, A273439, A273440, A273441. Main diagonal and first lower diagonal give: A000012, A045943. T(2n,n) gives A273442. Cf. A242027. Sequence in context: A259686 A162313 A188645 * A151918 A089974 A346039 Adjacent sequences:  A060278 A060279 A060280 * A060282 A060283 A060284 KEYWORD easy,nonn,tabl AUTHOR Vladeta Jovovic, Apr 09 2001 STATUS approved

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Last modified July 27 13:36 EDT 2021. Contains 346306 sequences. (Running on oeis4.)