a(0) = ... = a(3) = 1; a(n) = Sum_{k=0..n-4} Stirling2(n-4,k) * a(k).
A336021
a(0) = ... = a(3) = 1; a(n) = Sum_{k=0..n-4} Stirling2(n-4,k) * a(k).
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =2a(7) =5a(8) =15a(9) =52a(10) =204a(11) =902a(12) =4532a(13) =26196a(14) =175320a(15) =1351296a(16) =11819348a(17) =115309534a(18) =1236465988a(19) =14419850138a(20) =181652022376
External references
- oeis: A336021