The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 59th year, we have over 358,000 sequences, and we’ve crossed 10,300 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A019575 Place n distinguishable balls in n boxes (in n^n ways); let T(n,k) = number of ways that the maximum in any box is k, for 1 <= k <= n; sequence gives triangle of numbers T(n,k). 7
 1, 2, 2, 6, 18, 3, 24, 180, 48, 4, 120, 2100, 800, 100, 5, 720, 28800, 14700, 2250, 180, 6, 5040, 458640, 301350, 52920, 5292, 294, 7, 40320, 8361360, 6867840, 1342600, 153664, 10976, 448, 8, 362880, 172141200, 172872000, 36991080, 4644864, 387072, 20736, 648, 9 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS T(n,k) is the number of endofunctions on [n] such that the maximal cardinality of the nonempty preimages equals k. - Alois P. Heinz, Jul 31 2014 LINKS Alois P. Heinz, Rows n = 1..141, flattened FORMULA A019575(x, z) = Sum ( A049009(p)) where x = A036042(p), z = A049085(p) - Alford Arnold. From Robert Gerbicz, Aug 19 2010: (Start) Let f(n,k,b) = number of ways to place b balls to n boxes, where the max in any box is not larger than k. Then T(n,k) = f(n,k,n) - f(n,k-1,n). We have: f(n, k, b)=local(i); if(n==0, return(b==0));return(sum(i=0, min(k, b), binomial(b, i)*f(n-1, k, b-i))). T(n,k) = f(n,k,n) - f(n,k-1,n). (end) EXAMPLE Triangle begins: 1; 2, 2; 6, 18, 3; 24, 180, 48, 4; 120, 2100, 800, 100, 5; 720, 28800, 14700, 2250, 180, 6; 5040, 458640, 301350, 52920, 5292, 294, 7; 40320, 8361360, 6867840, 1342600, 153664, 10976, 448, 8; 362880, 172141200, 172872000, 36991080, 4644864, 387072, 20736, 648, 9; ... MAPLE b:= proc(n, i, k) option remember; `if`(n=0, 1, `if`(i<1, 0, add(b(n-j, i-1, k)/j!, j=0..min(k, n)))) end: T:= (n, k)-> n!* (b(n\$2, k) -b(n\$2, k-1)): seq(seq(T(n, k), k=1..n), n=1..12); # Alois P. Heinz, Jul 29 2014 MATHEMATICA f[0, _, b_] := Boole[b == 0]; f[n_, k_, b_] := f[n, k, b] = Sum[ Binomial[b, i]*f[n - 1, k, b - i], {i, 0, Min[k, b]}]; t[n_, k_] := f[n, k, n] - f[n, k - 1, n]; Flatten[ Table[ t[n, k], {n, 1, 9}, {k, 1, n}]] (* Jean-François Alcover, Mar 09 2012, after Robert Gerbicz *) PROG (PARI) /*setup memoization table for args <= M. Could be done dynamically inside f() */ M=10; F=vector(M, i, vector(M, i, vector(M))); f(n, k, b)={ (!n|!b|!k) & return(!b); F[n][k][b] & return(F[n][k][b]); F[n][k][b]=sum(i=0, min(k, b), binomial(b, i)*f(n-1, k, b-i)) } T(n, k)=f(n, k, n)-f(n, k-1, n) for(n=1, 9, print(vector(n, k, T(n, k)))) \\ M. F. Hasler, Aug 19 2010; Based on Robert Gerbicz's code I suggest the following (very naively) memoized version of "f" CROSSREFS Cf. A019576. See A180281 for the case when the balls are indistinguishable. Rows sums give A000312. Cf. A245687. Sequence in context: A006250 A006249 A216971 * A178882 A186195 A256215 Adjacent sequences: A019572 A019573 A019574 * A019576 A019577 A019578 KEYWORD nonn,tabl,easy,nice AUTHOR Lee Corbin (lcorbin(AT)tsoft.com) EXTENSIONS Edited by N. J. A. Sloane, Sep 06 2010 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 5 15:19 EST 2022. Contains 358588 sequences. (Running on oeis4.)