A128226 Triangle, A004736 * A127899 (unsigned).

1, 4, 2, 7, 7, 3, 10, 12, 10, 4, 13, 17, 17, 13, 5, 16, 22, 24, 22, 16, 6, 19, 27, 31, 31, 27, 19, 7, 22, 32, 38, 40, 38, 32, 22, 8, 25, 37, 45, 49, 49, 45, 37, 25, 9, 28, 42, 52, 58, 60, 58, 52, 42, 28, 10

Offset: 1

Author

Gary W. Adamson, Feb 19 2007

Keywords

• nonn
• tabl

Comments

Row sums = A084990: (1, 6, 17, 36, 65, 106, ...).

A128225 = A127899(unsigned) * A004736.

Examples

			First few row of the triangle are:
   1;
   4,  2;
   7,  7,  3;
  10, 12, 10,  4;
  13, 17, 17, 13,  5;
  16, 22, 24, 22, 16,  6;
  19, 27, 31, 31, 27, 19,  7;
  ...
		

Crossrefs

Cf. A004736, A084990, A127899, A128225.

Programs

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 *)

Formula

A004736 * A127899 (unsigned). By columns, (3k+1), (5k+2), (7k+3), ...; k=0,1,2...