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%I #5 Mar 12 2015 20:04:56
%S 1,1,3,1,2,6,1,2,3,10,1,2,3,4,6,1,2,3,4,5,10,1,2,3,4,5,6,15,1,2,3,4,5,
%T 6,7,8,1,2,3,4,5,6,7,8,13,1,2,3,4,5,6,7,8,9,19,1,2,3,4,5,6,7,8,9,10,
%U 26,1,2,3,4,5,6,7,8,9,10,11,15,1,2,3,4,5,6,7,8,9,10,11,12,22,1,2,3,4,5,6,7,8
%N Triangle read by rows in which the n-th row contains n distinct numbers whose sum is the smallest square.
%C If n(n+1)/2 is a square triangular number then the n-th row contains first n natural numbers (e.g., the 8th row).
%e 1; 1,3; 1,2,6; 1,2,3,10; 1,2,3,4,6; 1,2,3,4,5,10; 1,2,3,4,5,6,15; 1,2,3,4,5,6,...
%p seq(op([seq(i,i=1..n-1),(ceil(sqrt(n*(n+1)/2)))^2 - n*(n-1)/2]),n=1..15); # C. Ronaldo
%Y Cf. A080817, A080819, A080820.
%K nonn,tabl
%O 1,3
%A _Amarnath Murthy_, Mar 21 2003
%E More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 19 2004