Number of n-step walks from a universal vertex to the other on the diamond graph.

Terms

a(0) =0a(1) =1a(2) =2a(3) =5a(4) =14a(5) =33a(6) =90a(7) =221a(8) =582a(9) =1465a(10) =3794a(11) =9653a(12) =24830a(13) =63441a(14) =162762a(15) =416525a(16) =1067574a(17) =2733673a(18) =7003970a(19) =17938661a(20) =45954542a(21) =117709185a(22) =301527354a(23) =772364093a(24) =1978473510a(25) =5067929881a(26) =12981823922a(27) =33253543445a(28) =85180839134a(29) =218195012913