Number of 1-2-3-4 trees with n edges and with thinning limbs. A 1-2-3-4 tree is an ordered tree with vertices of outdegree at most 4. A rooted tree with thinning limbs is such that if a node has k children, all its children have at most k children.

A124499

Number of 1-2-3-4 trees with n edges and with thinning limbs. A 1-2-3-4 tree is an ordered tree with vertices of outdegree at most 4. A rooted tree with thinning limbs is such that if a node has k children, all its children have at most k children.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =10a(5) =24a(6) =62a(7) =160a(8) =425a(9) =1140a(10) =3105a(11) =8528a(12) =23643a(13) =66008a(14) =185526a(15) =524384a(16) =1489810a(17) =4251852a(18) =12184745a(19) =35048405a(20) =101156752a(21) =292865417a(22) =850314803a(23) =2475327088a(24) =7223400899a(25) =21126670372a(26) =61920289652a(27) =181838859665

External references