Numbers k that divide the k-th central Delannoy number.

Terms

a(0) =1a(1) =3a(2) =9a(3) =21a(4) =27a(5) =81a(6) =171a(7) =189a(8) =217a(9) =243a(10) =297a(11) =351a(12) =729a(13) =903a(14) =1547a(15) =2187a(16) =3591a(17) =3661a(18) =4131a(19) =5499a(20) =5967a(21) =6019a(22) =6561a(23) =7533a(24) =8001a(25) =11997a(26) =13203a(27) =14217a(28) =15309a(29) =17181