Numbers k that divide the k-th central trinomial coefficient.

Terms

a(0) =1a(1) =21a(2) =387a(3) =657a(4) =6291a(5) =16113a(6) =25767a(7) =54243a(8) =56457a(9) =96141a(10) =155601a(11) =294273a(12) =300871a(13) =453781a(14) =653421a(15) =660879a(16) =669609a(17) =951881a(18) =993307a(19) =1246077a(20) =1438623a(21) =1535409a(22) =1870533a(23) =2110941a(24) =2510109a(25) =2959173a(26) =2974239a(27) =3158541a(28) =3242673a(29) =3569337