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 A135223 Triangle A000012 * A127648 * A103451, read by rows. 2
 1, 3, 2, 6, 2, 3, 10, 2, 3, 4, 15, 2, 3, 4, 5, 21, 2, 3, 4, 5, 6, 28, 2, 3, 4, 5, 6, 7, 36, 2, 3, 4, 5, 6, 7, 8, 45, 2, 3, 4, 5, 6, 7, 8, 9, 55, 2, 3, 4, 5, 6, 7, 8, 9, 10, 66, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 78, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 91, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Row sums = A028387. LINKS G. C. Greubel, Rows n = 1..100 of triangle, flattened FORMULA T(n,k) = A000012(n,k) * A127648(n,k) * A103451(n,k) as infinite lower triangular matrices. Replace left border of 1's in A002260 with (1, 3, 6, 10, 15,...). T(n, k) = k with T(n,1) = binomial(n+1, 2). - G. C. Greubel, Nov 20 2019 EXAMPLE First few rows of the triangle are:    1;    3, 2;    6, 2, 3;   10, 2, 3, 4;   15, 2, 3, 4, 5; ... MAPLE seq(seq( `if`(k=1, binomial(n+1, 2), k), k=1..n), n=1..15); # G. C. Greubel, Nov 20 2019 MATHEMATICA T[n_, k_]:= T[n, k]= If[k==1, Binomial[n+1, 2], k]; Table[T[n, k], {n, 15}, {k, n}]//Flatten (* G. C. Greubel, Nov 20 2019 *) PROG (PARI) T(n, k) = if(k==1, binomial(n+1, 2), k); \\ G. C. Greubel, Nov 20 2019 (MAGMA) [k eq 1 select Binomial(n+1, 2) else k: k in [1..n], n in [1..15]]; // G. C. Greubel, Nov 20 2019 (Sage) @CachedFunction def T(n, k):     if (k==1): return binomial(n+1, 2)     else: return k [[T(n, k) for k in (1..n)] for n in (1..15)] # G. C. Greubel, Nov 20 2019 (GAP) T:= function(n, k)     if k=1 then return Binomial(n+1, 2);     else return k;     fi; end; Flat(List([1..15], n-> List([1..n], k-> T(n, k) ))); # G. C. Greubel, Nov 20 2019 CROSSREFS Cf. A002260, A103451, A127648. Sequence in context: A188614 A290798 A133519 * A143310 A131897 A061187 Adjacent sequences:  A135220 A135221 A135222 * A135224 A135225 A135226 KEYWORD nonn,tabl AUTHOR Gary W. Adamson, Nov 23 2007 EXTENSIONS More terms added by G. C. Greubel, Nov 20 2019 STATUS approved

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Last modified April 22 07:26 EDT 2021. Contains 343163 sequences. (Running on oeis4.)