Number of set partitions of length <= 4; sum of first 4 columns of triangle of Stirling numbers of 2nd kind; dimension of space of symmetric polynomials in 4 noncommuting variables.
A124303
Number of set partitions of length <= 4; sum of first 4 columns of triangle of Stirling numbers of 2nd kind; dimension of space of symmetric polynomials in 4 noncommuting variables.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =5a(4) =15a(5) =51a(6) =187a(7) =715a(8) =2795a(9) =11051a(10) =43947a(11) =175275a(12) =700075a(13) =2798251a(14) =11188907a(15) =44747435a(16) =178973355a(17) =715860651a(18) =2863377067a(19) =11453377195a(20) =45813246635a(21) =183252462251a(22) =733008800427
External references
- oeis: A124303