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A130270 Triangle read by rows, T(n) followed by 1, 2, 3, ..., n-1.

%I A130270 #8 Feb 08 2022 19:15:33
%S A130270 1,3,1,6,1,2,10,1,2,3,15,1,2,3,4,21,1,2,3,4,5,28,1,2,3,4,5,6,36,1,2,3,
%T A130270 4,5,6,7,45,1,2,3,4,5,6,7,8
%N A130270 Triangle read by rows, T(n) followed by 1, 2, 3, ..., n-1.
%C A130270 Row sums = n^2.
%H A130270 Harvey P. Dale, <a href="/A130270/b130270.txt">Table of n, a(n) for n = 1..1000</a>
%F A130270 Triangle read by rows, T(n) followed by 1,2,3,...,n-1. Row differences of triangle A130269 starting from the left.
%e A130270 First few rows of the triangle:
%e A130270    1;
%e A130270    3, 1;
%e A130270    6, 1, 2;
%e A130270   10, 1, 2, 3;
%e A130270   15, 1, 2, 3, 4;
%e A130270   ...
%e A130270 Row 4 = (10, 1, 2, 3) = differences of row 4 of A130269: (10, 11, 13, 16).
%t A130270 Table[Join[{(n(n+1))/2,Range[n-1]}],{n,10}]//Flatten (* _Harvey P. Dale_, Dec 31 2021 *)
%Y A130270 Cf. A000217, A130269.
%K A130270 nonn,tabl
%O A130270 1,2
%A A130270 _Gary W. Adamson_, May 18 2007