Number of odd-length columns in all bargraphs having semiperimeter n (n>=2).

Terms

a(0) =1a(1) =2a(2) =6a(3) =20a(4) =64a(5) =204a(6) =656a(7) =2120a(8) =6873a(9) =22350a(10) =72881a(11) =238232a(12) =780384a(13) =2561164a(14) =8419766a(15) =27721784a(16) =91397927a(17) =301710074a(18) =997087170a(19) =3298556716a(20) =10922576840a(21) =36199599880a(22) =120068987717a(23) =398547827336