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

 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-François 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.

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