A246574 a(n) = 2*(n-1)*Catalan(n).

0, 4, 20, 84, 336, 1320, 5148, 20020, 77792, 302328, 1175720, 4576264, 17829600, 69535440, 271455660, 1060730100, 4148633280, 16239715800, 63621474840, 249436575960, 978650680800, 3842267672880, 15094623000600, 59335590776904, 233373427269696

Offset: 1

Author

N. J. A. Sloane, Aug 30 2014

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000
• Igor Pak, History of Catalan numbers, arXiv:1408.5711 [math.HO], 2014. See Section 5, A_n.

Crossrefs

Cf. A000108, A024483.

Programs

Magma

[2*(n-1)*Catalan(n): n in [1..30]]; // Vincenzo Librandi, Aug 31 2014

Mathematica

Table[2 (CatalanNumber[n] (n - 1)), {n, 1, 30}] (* Vincenzo Librandi, Aug 31 2014 *)