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%I #5 Feb 08 2022 20:18:58
%S 1,4,2,5,7,3,6,8,10,4,7,9,11,13,5,8,10,12,14,16,6,9,11,13,15,17,19,7,
%T 10,12,14,16,18,20,22,8,11,13,15,17,19,21,23,25,9,12,14,16,18,20,22,
%U 24,26,28,10
%N Triangle read by rows: a(1) = 1; then n-th row = n terms of (n+2), (n+4), (n+6), ..., n.
%C Row sums = the hexagonal numbers, A000384: (1, 6, 15, 28, 45, 66, 91, ...).
%e First few rows of the triangle:
%e 1;
%e 4, 2;
%e 5, 7, 3;
%e 6, 8, 10, 4;
%e 7, 9, 11, 13, 5;
%e 8, 10, 12, 14, 16, 6;
%e 9, 11, 13, 15, 17, 19, 7;
%e ...
%Y Cf. A000384.
%K nonn,tabl
%O 1,2
%A _Gary W. Adamson_, Oct 14 2007