a(n) = (-1/2)*Sum_{i1 + i2 + i3 = 2*n} ((2*n)!/(i1! i2! i3!))*B(i1), where B are the Bernoulli numbers (with i1, i2, i3 >= 1).
A124133
a(n) = (-1/2)*Sum_{i1 + i2 + i3 = 2*n} ((2*n)!/(i1! i2! i3!))*B(i1), where B are the Bernoulli numbers (with i1, i2, i3 >= 1).
Terms
- a(0) =0a(1) =5a(2) =28a(3) =123a(4) =506a(5) =2041a(6) =8184a(7) =32759a(8) =131062a(9) =524277a(10) =2097140a(11) =8388595a(12) =33554418a(13) =134217713a(14) =536870896a(15) =2147483631a(16) =8589934574a(17) =34359738349a(18) =137438953452a(19) =549755813867
External references
- oeis: A124133