A164863 Number of ways of placing n labeled balls into 9 indistinguishable boxes; word structures of length n using a 9-ary alphabet.

1, 1, 2, 5, 15, 52, 203, 877, 4140, 21147, 115974, 678514, 4211825, 27602602, 190077045, 1368705291, 10254521370, 79527284317, 635182667816, 5199414528808, 43426867585575, 368654643520692, 3170300933550687, 27542984610086665, 241205285284001240

Offset

0,3

Links

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Joerg Arndt and N. J. A. Sloane, Counting Words that are in "Standard Order"

Moreira, N.; Reis, R. "On the Density of Languages Representing Finite Set Partitions", Journal of Integer Sequences, Vol. 8 (2005), Article 05.2.8.

Pierpaolo Natalini, Paolo Emilio Ricci, New Bell-Sheffer Polynomial Sets, Axioms 2018, 7(4), 71.

Eric Weisstein's World of Mathematics, Set Partition

Formula

a(n) = Sum_{k=0..9} stirling2 (n,k).

a(n) = ceiling (103/560*2^n +53/864*3^n +11/720*4^n +5^n/320 +6^n/2160 +7^n/10080 +9^n/362880).

G.f.: (16687*x^8 -67113*x^7 +88620*x^6 -56993*x^5 +20529*x^4 -4353*x^3 +539*x^2 -36*x+1) / ((9*x-1) *(7*x-1) *(6*x-1) *(5*x-1) *(4*x-1) *(3*x-1) *(2*x-1) *(x-1)).

G.f.: Sum_{j=0..k} A248925(k,j)*x^j / Product_{j=1..k} 1-j*x with k=9. - Robert A. Russell, Apr 25 2018

Maple

# first program:
a:= n-> ceil(103/560*2^n +53/864*3^n +11/720*4^n +5^n/320 +6^n/2160 +7^n/10080 +9^n/362880): seq(a(n), n=0..25);
# second program:
a:= n-> add(Stirling2(n, k), k=0..9): seq(a(n), n=0..25);

Mathematica

Table[Sum[StirlingS2[n, k], {k, 0, 9}], {n, 0, 30}] (* Robert A. Russell, Apr 25 2018 *)

Crossrefs

Cf. A000110, A048993, A008291, A098825, A000012, A000079, A007051, A007581, A124303, A056272, A056273, A099262, A099263, A164864.

A row of the array in A278984.

Sequence in context: A287280 A287258 A287670 * A192126 A229226 A343671

Adjacent sequences: A164860 A164861 A164862 * A164864 A164865 A164866

Keyword

easy,nonn

Author

Alois P. Heinz, Aug 28 2009

Status

approved