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 A121334 Triangle, read by rows, where T(n,k) = C( n*(n+1)/2 + n-k, n-k), for n>=k>=0. 5
 1, 2, 1, 10, 4, 1, 84, 28, 7, 1, 1001, 286, 66, 11, 1, 15504, 3876, 816, 136, 16, 1, 296010, 65780, 12650, 2024, 253, 22, 1, 6724520, 1344904, 237336, 35960, 4495, 435, 29, 1, 177232627, 32224114, 5245786, 749398, 91390, 9139, 703, 37, 1, 5317936260 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS A triangle having similar properties and complementary construction is the dual triangle A122175. LINKS FORMULA Remarkably, row n of the matrix inverse (A121439) equals row n of A121412^(-n*(n+1)/2-1). Further, the following matrix products of triangles of binomial coefficients are equal: A121412 = A121334*A122178^-1 = A121335*A121334^-1 = A121336*A121335^-1, where row n of H=A121412 equals row (n-1) of H^(n+1) with an appended '1'. EXAMPLE Triangle begins: 1; 2, 1; 10, 4, 1; 84, 28, 7, 1; 1001, 286, 66, 11, 1; 15504, 3876, 816, 136, 16, 1; 296010, 65780, 12650, 2024, 253, 22, 1; 6724520, 1344904, 237336, 35960, 4495, 435, 29, 1; 177232627, 32224114, 5245786, 749398, 91390, 9139, 703, 37, 1; ... PROG (PARI) T(n, k)=binomial(n*(n+1)/2+n-k, n-k) CROSSREFS Cf. A121439 (matrix inverse); A121412; variants: A122178, A121335, A121336; A122175 (dual). Sequence in context: A110327 A105615 A136216 * A126450 A235608 A112333 Adjacent sequences:  A121331 A121332 A121333 * A121335 A121336 A121337 KEYWORD nonn,tabl AUTHOR Paul D. Hanna, Aug 29 2006 STATUS approved

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Last modified August 24 16:10 EDT 2019. Contains 326295 sequences. (Running on oeis4.)