a(n) = Sum_{k=0..floor(n/2)} binomial(2n-2k,2k)10^(n-k).
A108487
a(n) = Sum_{k=0..floor(n/2)} binomial(2n-2k,2k)10^(n-k).
Terms
- a(0) =1a(1) =10a(2) =110a(3) =1600a(4) =25100a(5) =395000a(6) =6201000a(7) =97280000a(8) =1526010000a(9) =23938500000a(10) =375525100000
External references
- oeis: A108487