A278883 a(n) = (4*n+1) * ( binomial(3*n,n)/(2*n+1) )^2.

1, 5, 81, 1872, 51425, 1565109, 50979600, 1742711616, 61765676577, 2251396558125, 83924761860225, 3186277484832000, 122829049870699536, 4796448751641900752, 189381233826675892800, 7549371503605704934656, 303473219026059360959265, 12289574902507266828093525, 500960076377670398672062425, 20540854991655352005504930000, 846696245823312839372671355025, 35068049224094584278339245227125, 1458752047374053912228252043321600

Offset: 0

Author

Paul D. Hanna, Nov 29 2016

Keywords

• nonn

Comments

Central terms of triangle A278880; a(n) = A278880(2*n+1, n) for n>=0.

Crossrefs

Cf. A278880.

Programs

PARI

{a(n) = (4*n+1) * ( binomial(3*n,n)/(2*n+1) )^2}
for(n=0,20,print1(a(n),", "))