Search: id:A085483
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%I A085483
%S A085483 2,2,5,2,15,14,2,35,84,43,2,75,350,430,142,2,155,1260,2795,2130,499,2,
%T A085483 315,4214,15050,19880,10479,1850,2,635,13524,73143,149100,132734,51800,
%U A085483 7193,2,1275,42350,334110,987042,1320354,854700,258948,29186,2,2555
%N A085483 Triangle read by rows: S_B(n,k) = `Type B' Stirling numbers of the second 
               kind.
%F A085483 A partition of {-n, ..., -1, 1, ..., n} into nonempty subsets X_1, ..., 
               X_r is called `symmetric' if for each i -X_i = X_j for some j. S_B(n, 
               k) is the number of such symmetric partitions whose induced partition 
               on {1, ..., n} involves k nonempty subsets. S_B(n, k) = S(n, k) * 
               a(k), where S(n, k) is A008277 and a(k) is A005425.
%e A085483 S_B(2,2)=5 because the relevant partitions of {-2,-1,1,2} are: {-2|-1|1|2}, 
               {-1,1|-2|2}, {-1|1|-2,2}, {-1,1|-2,2}, {1,-2|-1,2}.
%Y A085483 Cf. A008277, A005425.
%Y A085483 S_B(n, 1)+...+S_B(n, n) = A002872(n).
%Y A085483 Sequence in context: A068058 A144943 A114976 this_sequence A038041 A097891 
               A097611
%Y A085483 Adjacent sequences: A085480 A085481 A085482 this_sequence A085484 A085485 
               A085486
%K A085483 nonn,tabl
%O A085483 1,1
%A A085483 James East (jameseastseq(AT)hotmail.com), Aug 15 2003

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