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 A258281 Number of partitions of 3 copies of n into distinct parts. 2
 1, 1, 4, 5, 13, 18, 37, 56, 103, 154, 279, 398, 682, 1027, 1664, 2433, 3977, 5755, 8957, 13173, 19980, 29002, 43894, 62562, 92531, 133550, 193348, 274049, 398218, 558839, 796906, 1120833, 1577874, 2197279, 3089063, 4258348, 5915878, 8170572, 11231601, 15355764 (list; graph; refs; listen; history; text; internal format)
 OFFSET 5,3 LINKS Alois P. Heinz, Table of n, a(n) for n = 5..200 FORMULA a(n) = 1/6 * [(x*y*z)^n] Product_{j>0} (1+x^j+y^j+z^j). EXAMPLE a(7) = 4: [7;6,1;5,2], [7;6,1;4,3], [7;5,2;4,3], [6,1;5,2;4,3]. MATHEMATICA nmax = 30; p = 1; Do[p = Expand[p*(1 + x^j + y^j + z^j)]; p = Select[p, (Exponent[#, x] <= nmax) && (Exponent[#, y] <= nmax) && (Exponent[#, z] <= nmax) &], {j, 1, nmax}]; p = Select[p, Exponent[#, x] == Exponent[#, y] == Exponent[#, z] &]; Table[Coefficient[p, x^n*y^n*z^n]/6, {n, 5, nmax}] (* Vaclav Kotesovec, Apr 07 2017 *) CROSSREFS Column k=3 of A258280. Sequence in context: A083709 A091183 A234254 * A094029 A005672 A147001 Adjacent sequences: A258278 A258279 A258280 * A258282 A258283 A258284 KEYWORD nonn AUTHOR Alois P. Heinz, May 25 2015 STATUS approved

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Last modified June 1 03:55 EDT 2023. Contains 363068 sequences. (Running on oeis4.)