> This, i believe, leads to the formula > > a(n) = > 0 if n == 0 (mod 4) > A007947(n)/2 if n == 2 (mod 4) > A007947(n) if n == 1 (mod 2) > > The problem is to show that the sequence definition is equivalent to one of > these characterizations. Also, what can be said about A076107? ralf