a(n) = binomial(Bell(n), 2) where B(n) = Bell numbers A000110(n).

A193274

a(n) = binomial(Bell(n), 2) where B(n) = Bell numbers A000110(n).

Terms

    a(0) =0a(1) =0a(2) =1a(3) =10a(4) =105a(5) =1326a(6) =20503a(7) =384126a(8) =8567730a(9) =223587231a(10) =6725042325a(11) =230228283165

External references