Third row or column of table A205497.

Terms

a(0) =1a(1) =14a(2) =109a(3) =623a(4) =2951a(5) =12331a(6) =47191a(7) =169416a(8) =579889a(9) =1914226a(10) =6144668a(11) =19298724a(12) =59579803a(13) =181448918a(14) =546629054a(15) =1632497850a(16) =4841448042a(17) =14277423006a(18) =41912838982a(19) =122587133760a(20) =357476552161