%I A001283
%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 m consists of m(m+1), ..., m(2m-1).
%C A001283 With a different offset: triangle read by rows: T(n,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 (fvlamoen(AT)hotmail.com), 
               Aug 21 2001
%e A001283 6; 12,15; 20,24,28; 30,35,40,45; 42,48,54,60,66; ...
%Y A001283 Cf. A003991, A063929, A063930.
%Y A001283 Row sums are in A085788. Central column is A033581.
%Y A001283 Sequence in context: A129494 A001284 A063931 this_sequence A106430 A106420 
               A081535
%Y A001283 Adjacent sequences: A001280 A001281 A001282 this_sequence A001284 A001285 
               A001286
%K A001283 nonn,easy,tabl
%O A001283 2,1
%A A001283 N. J. A. Sloane (njas(AT)research.att.com).