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 A278883 a(n) = (4*n+1) * ( binomial(3*n,n)/(2*n+1) )^2. 1
 1, 5, 81, 1872, 51425, 1565109, 50979600, 1742711616, 61765676577, 2251396558125, 83924761860225, 3186277484832000, 122829049870699536, 4796448751641900752, 189381233826675892800, 7549371503605704934656, 303473219026059360959265, 12289574902507266828093525, 500960076377670398672062425, 20540854991655352005504930000, 846696245823312839372671355025, 35068049224094584278339245227125, 1458752047374053912228252043321600 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Central terms of triangle A278880; a(n) = A278880(2*n+1, n) for n>=0. LINKS PROG (PARI) {a(n) = (4*n+1) * ( binomial(3*n, n)/(2*n+1) )^2} for(n=0, 20, print1(a(n), ", ")) CROSSREFS Cf. A278880. Sequence in context: A335177 A135918 A115032 * A307376 A009733 A009756 Adjacent sequences: A278880 A278881 A278882 * A278884 A278885 A278886 KEYWORD nonn AUTHOR Paul D. Hanna, Nov 29 2016 STATUS approved

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Last modified March 20 22:04 EDT 2023. Contains 361391 sequences. (Running on oeis4.)