a(n) = S1(n,3), where S1(n, t) = Sum_{k=0..n} (k^t * Sum_{j=0..k} binomial(n,j)).
A089660
a(n) = S1(n,3), where S1(n, t) = Sum_{k=0..n} (k^t * Sum_{j=0..k} binomial(n,j)).
Terms
- a(0) =0a(1) =2a(2) =35a(3) =276a(4) =1522a(5) =6820a(6) =26664a(7) =94640a(8) =312512a(9) =975744a(10) =2913280a(11) =8386048a(12) =23416320a(13) =63724544a(14) =169637888a(15) =443043840a(16) =1137934336a(17) =2879979520a(18) =7194083328a(19) =17761304576a(20) =43390730240a(21) =104997322752a(22) =251881062400a(23) =599482433536
External references
- oeis: A089660