a(n) = Sum_{k=0..n} binomial(floor((n+1)/2), floor((k+1)/2)) * 4^k.
A097175
a(n) = Sum_{k=0..n} binomial(floor((n+1)/2), floor((k+1)/2)) * 4^k.
Terms
- a(0) =1a(1) =5a(2) =21a(3) =105a(4) =361a(5) =2045a(6) =6141a(7) =38865a(8) =104401a(9) =726245a(10) =1774821a(11) =13394745a(12) =30171961a(13) =244487885a(14) =512923341a(15) =4424729505a(16) =8719696801a(17) =79515368885a(18) =148234845621
External references
- oeis: A097175