38946domain: NAppears in sequencesa(0) = 1; a(n) = 6 * Sum_{k=1..n} binomial(n,k) * a(k-1).at n=5A345077Expansion of Sum_{k>0} x^(2*k)/(1-x^k)^5.at n=29A363605Number of defective (binary) heaps on n elements from the set {0,1} where exactly n ancestor-successor pairs do not have the correct order.at n=20A372641