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A001283 Triangle read by rows, in which row n consists of n(n+m) for m = 1 .. n-1.

%I A001283 #24 Feb 03 2022 00:32:10
%S A001283 6,12,15,20,24,28,30,35,40,45,42,48,54,60,66,56,63,70,77,84,91,72,80,
%T A001283 88,96,104,112,120,90,99,108,117,126,135,144,153,110,120,130,140,150,
%U A001283 160,170,180,190,132,143,154,165,176,187,198,209,220,231,156,168,180
%N A001283 Triangle read by rows, in which row n consists of n(n+m) for m = 1 .. n-1.
%C A001283 With a different offset: triangle read by rows: t(n, m) = T(n+1, m) = (n+1)(n+m+1) = radius of C-excircle of Pythagorean triangle with sides a=(n+1)^2-m^2, b=2*(n+1)*m and c=(n+1)^2+m^2. - _Floor van Lamoen_, Aug 21 2001
%H A001283 T. D. Noe, <a href="/A001283/b001283.txt">Rows n = 2..100, flattened</a>
%F A001283 T(n, m) = n*(n+m), n-1 >= m >= 1.
%e A001283 The triangle T(n, m) begins:
%e A001283 n\m   1   2   3   4   5   6   7   8   9  10  11  12  13  14 ...
%e A001283 2:    6
%e A001283 3:   12  15
%e A001283 4:   20  24  28
%e A001283 5:   30  35  40  45
%e A001283 6:   42  48  54  60  66
%e A001283 7:   56  63  70  77  84  91
%e A001283 8:   72  80  88  96 104 112 120
%e A001283 9:   90  99 108 117 126 135 144 153
%e A001283 10: 110 120 130 140 150 160 170 180 190
%e A001283 11: 132 143 154 165 176 187 198 209 220 231
%e A001283 12: 156 168 180 192 204 216 228 240 252 264 276
%e A001283 13: 182 195 208 221 234 247 260 273 286 299 312 325
%e A001283 14: 210 224 238 252 266 280 294 308 322 336 350 364 378
%e A001283 15: 240 255 270 285 300 315 330 345 360 375 390 405 420 435
%e A001283 ...
%e A001283 [Reformatted and extended by _Wolfdieter Lang_, Dec 02 2014]
%e A001283 ----------------------------------------------------------------
%t A001283 Flatten[Table[n*(n+m), {n, 2, 10}, {m, n-1}]] (* _T. D. Noe_, Jun 27 2012 *)
%Y A001283 Cf. A003991, A063929, A063930.
%Y A001283 Row sums are in A085788. Central column is A033581.
%K A001283 nonn,easy,tabl
%O A001283 2,1
%A A001283 _N. J. A. Sloane_
%E A001283 Edited comment by _Wolfdieter Lang_, Dec 02 2014