A055220 T(2n+4,n), array T as in A055216.
1, 6, 28, 113, 423, 1507, 5193, 17469, 57720, 188098, 606336, 1937490, 6146895, 19386189, 60836271, 190104957, 591899346, 1837128933, 5686494333, 17559366768, 54107166250, 166412478896, 510963917688, 1566546588694
Offset: 0