A128225 A127899 (unsigned) * A004736.
1, 6, 2, 15, 9, 3, 28, 20, 12, 4, 45, 35, 25, 15, 5, 66, 54, 42, 30, 18, 6, 91, 77, 63, 49, 35, 21, 7, 120, 104, 88, 72, 56, 40, 24, 8, 153, 135, 117, 99, 81, 63, 45, 27, 9, 190, 170, 150, 130, 110, 90, 70, 50, 30, 10
Offset: 1
Examples
First few rows of the triangle are: 1; 6, 2; 15, 9, 3; 28, 20, 12, 4; 45, 35, 25, 15, 5; 66, 54, 42, 30, 18, 6; 91, 77, 63, 49, 35, 21, 7; ...
Programs
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Mathematica
(* a127899U computes the unsigned version of A127899 *) a127899U[n_, k_] := If[n==k||n-1==k, n, 0]/;(1<=k<=n) a004736[n_, k_] := n-k+1/;(1<=k<=n+1) a128225[n_, k_] := a127899U[n, n](a004736[n, k] + a004736[n-1, k])/;(1<=k<=n) a128225[r_] := Table[a128225[n, k], {n, 1, r}, {k, 1, n}] TableForm[a128225[7]] (* triangle *) Flatten[a128225[10]] (* data *) (* Hartmut F. W. Hoft, Mar 13 2017 *)
Comments