a(n) = Sum_{k>=1} k^(2*n)/(2^k).A227044a(n) = Sum_{k>=1} k^(2*n)/(2^k).Terms a(0) =1a(1) =6a(2) =150a(3) =9366a(4) =1091670a(5) =204495126a(6) =56183135190External referencesoeis: A227044