First column of A261987.

Terms

a(0) =4a(1) =8a(2) =25a(3) =91a(4) =115a(5) =527a(6) =527a(7) =1331a(8) =1331a(9) =4301a(10) =15689a(11) =14111a(12) =19337a(13) =31427a(14) =175151a(15) =175151a(16) =175151a(17) =175151a(18) =175151