Duplicate of A172634.

Terms

a(0) =1a(1) =1a(2) =7a(3) =31a(4) =175a(5) =991a(6) =5881a(7) =35617a(8) =219871a(9) =1376095a(10) =8710537a(11) =55644337a(12) =358198369a(13) =2320792657a(14) =15120204295a(15) =98984058271a(16) =650725327231