login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A272519 Number of set partitions of [n] into seven blocks with distinct sizes. 2
2431106898187968000, 8812762505931384000, 67144857188048640000, 416298114565901568000, 3144312274410635328000, 23728992530256389376000, 238675412699786289427200, 3207620559498676985664000, 16207982672116390803648000, 117220515926387332979520000 (list; graph; refs; listen; history; text; internal format)
OFFSET

28,1

LINKS

Alois P. Heinz, Table of n, a(n) for n = 28..1000

FORMULA

a(n) = n! * [x^n*y^7] Product_{n>=1} (1+y*x^n/n!).

MAPLE

b:= proc(n, i, t) option remember; `if`(t>i or t*(t+1)/2>n

      or t*(2*i+1-t)/2<n, 0, `if`(n=0, 1, b(n, i-1, t)+

      `if`(i>n, 0, b(n-i, i-1, t-1)*binomial(n, i))))

    end:

a:= n-> b(n$2, 7):

seq(a(n), n=28..40);

MATHEMATICA

b[n_, i_, t_] := b[n, i, t] = If[t > i || t*(t + 1)/2 > n || t*(2*i + 1 - t)/2 < n, 0, If[n == 0, 1, b[n, i - 1, t] + If[i > n, 0, b[n - i, i - 1, t - 1]*Binomial[n, i]]]];

a[n_] := b[n, n, 7];

Table[a[n], {n, 28, 40}] (* Jean-François Alcover, May 24 2018, translated from Maple *)

CROSSREFS

Column k=7 of A131632.

Sequence in context: A281509 A115539 A080129 * A246234 A274814 A323534

Adjacent sequences:  A272516 A272517 A272518 * A272520 A272521 A272522

KEYWORD

nonn

AUTHOR

Alois P. Heinz, May 01 2016

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 24 09:40 EST 2020. Contains 332209 sequences. (Running on oeis4.)