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A123326 Let M be the matrix defined in A111490. Sequence gives the sum of the elements of the submatrices (from the upper left element): M(1,1); M(1,1)+M(1,2)+M(1,2)+M(2,2); M(1,1)+M(1,2)+M(1,3)+M(2,1)+M(2,2)+M(2,3)+M(3,1)+M(3,2)+M(3,3), etc.

%I A123326 #20 May 06 2021 08:23:57
%S A123326 1,5,13,27,47,77,114,165,226,302,391,502,622,768,933,1120,1325,1564,
%T A123326 1819,2112,2424,2768,3143,3564,3998,4477,4993,5551,6138,6783,7447,
%U A123326 8173,8933,9745,10606,11525,12462,13473,14539,15667,16826,18067,19339,20697,22104
%N A123326 Let M be the matrix defined in A111490. Sequence gives the sum of the elements of the submatrices (from the upper left element): M(1,1); M(1,1)+M(1,2)+M(1,2)+M(2,2); M(1,1)+M(1,2)+M(1,3)+M(2,1)+M(2,2)+M(2,3)+M(3,1)+M(3,2)+M(3,3), etc.
%F A123326 a(n) = Sum_{i=1..n} Sum_{j=1..n} M(i,j).
%F A123326 a(n) = a(n-1) + A121896(n) with a(0)=0.
%e A123326 a(4) = 1+1+1+1 + 1+2+1+2 + 1+2+3+1 + 1+2+3+4 = 27.
%Y A123326 Cf. A111490, A121896.
%K A123326 easy,nonn
%O A123326 1,2
%A A123326 _Paolo P. Lava_ and _Giorgio Balzarotti_, Sep 26 2006