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 A128569 Column 2 of triangle A128567. 3
 1, 14, 117, 813, 4871, 27743, 151208, 804065, 4185683, 21472005, 108766010, 545507633, 2712801330, 13394412999, 65722444172, 320721839860, 1557502222385, 7530671086667, 36267851679585, 174038009185816, 832392015517829, 3969017685816667, 18871416851149078 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS A128567 is the matrix square of Parker's partition triangle A047812. LINKS FORMULA a(n) = Sum_{s=2..n+2} A047812(n+3,s)*A047812(s+1,2) for n >= 0. - Petros Hadjicostas, May 31 2020 PROG (PARI) {a(n)=local(M); M=matrix(n+3, n+3, r, c, if(r

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Last modified December 1 12:50 EST 2020. Contains 338833 sequences. (Running on oeis4.)