A128222 - OEIS

%I #11 Feb 18 2022 22:08:13

%S 1,1,2,3,1,3,1,4,1,4,5,1,5,1,5,1,6,1,6,1,6,7,1,7,1,7,1,7,1,8,1,8,1,8,

%T 1,8,9,1,9,1,9,1,9,1,9,1,10,1,10,1,10,1,10,1,10

%N A127701 * A128174.

%C Row sums = A128223: (1, 3, 7, 10, 17, 21, 31, 36, ...).

%F A127701 * A128174 as infinite lower triangular matrices. Odd rows: n terms of n, 1, n, ...; even rows: n terms of 1, n, 1, ...

%e First few rows of the triangle:

%e   1;

%e   1, 2;

%e   3, 1, 3;

%e   1, 4, 1, 4;

%e   5, 1, 5, 1, 5;

%e   1, 6, 1, 6, 1, 6;

%e   7, 1, 7, 1, 7, 1, 7;

%e   ...

%t a128222[n_, k_] := If[EvenQ[n-k], n, 1]/;1<=k<=n

%t a128222[r_] := Table[a128222[n, k], {n, 1, r}, {k, 1, n}]

%t TableForm[a128222[7]] (* triangle *)

%t Flatten[a128222[10]] (* data *) (* _Hartmut F. W. Hoft_, Mar 08 2017 *)

%Y Cf. A127701, A128174, A128223, A128222.

%K nonn,tabl

%O 1,3

%A _Gary W. Adamson_, Feb 19 2007

%E Inserted omitted values a(28) = 7 and a(29) = 1, _Hartmut F. W. Hoft_, Mar 08 2017