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 A277584 a(n) = binomial(3n-1, n-1)^2. 1
 0, 1, 25, 784, 27225, 1002001, 38291344, 1502337600, 60101954649, 2440703175625, 100300325150025, 4161829109817600, 174077451630810000, 7330421677037621904, 310467090932230849600, 13214837914326197526784, 564927069263895118093401 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Seiichi Manyama, Table of n, a(n) for n = 0..605 FORMULA a(n) = A025174(n)^2. a(n) = A188662(n)/9 for n > 0. Let the number of multisets of length k on n symbols be denoted by ((n, k)) = binomial(n+k-1, k). a(n) = (Sum_{k=0..n} binomial(n, k)^2 * ((2*n, 2*n - k)))/5 for n > 0. MATHEMATICA Table[Boole[n > 0] Binomial[3 n - 1, n - 1]^2, {n, 0, 16}] (* Michael De Vlieger, Oct 26 2016 *) PROG (PARI) a(n) = binomial(3*n-1, n-1)^2; \\ Michel Marcus, Oct 22 2016 (Magma) [Binomial(3*n-1, n-1)^2: n in [0..20]]; // Vincenzo Librandi, Oct 23 2016 CROSSREFS Cf. A025174, A060150, A188662. Sequence in context: A286439 A123835 A012835 * A223228 A132540 A337247 Adjacent sequences: A277581 A277582 A277583 * A277585 A277586 A277587 KEYWORD nonn AUTHOR Seiichi Manyama, Oct 22 2016 STATUS approved

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Last modified March 25 08:54 EDT 2023. Contains 361520 sequences. (Running on oeis4.)