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!)
A193274 a(n) = binomial(Bell(n), 2) where B(n) = Bell numbers A000110(n). 3
0, 0, 1, 10, 105, 1326, 20503, 384126, 8567730, 223587231, 6725042325, 230228283165, 8877197732406, 382107434701266, 18221275474580181, 956287167902779240, 54916689705422813731, 3433293323775503064306, 232614384749689991763561, 17010440815323680947084096 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..300

Frank Ruskey and Jennifer Woodcock, The Rand and block distances of pairs of set partitions, in International Workshop on Combinatorial Algorithms, Victoria, 2011. LNCS.

Frank Ruskey, Jennifer Woodcock and Yuji Yamauchi, Counting and computing the Rand and block distances of pairs of set partitions, Journal of Discrete Algorithms, Volume 16, October 2012, Pages 236-248. - From N. J. A. Sloane, Oct 03 2012

MAPLE

a:= n-> binomial(combinat[bell](n), 2):

seq(a(n), n=0..20);  # Alois P. Heinz, Aug 28 2011

MATHEMATICA

a[n_] := With[{b = BellB[n]}, b*(b-1)/2]; Table[a[n], {n, 0, 19}] (* Jean-Fran├žois Alcover, Mar 18 2014 *)

PROG

(MAGMA) [Binomial(Bell(n), 2): n in [0..20]]; // Vincenzo Librandi, Feb 17 2018

CROSSREFS

Row sums of A193297.

Sequence in context: A000457 A240681 A113348 * A068883 A087599 A226360

Adjacent sequences:  A193271 A193272 A193273 * A193275 A193276 A193277

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Aug 26 2011

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 27 03:50 EST 2020. Contains 332299 sequences. (Running on oeis4.)