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%I #8 May 07 2014 16:45:30
%S 1,-1,2,2,-1,-1,3,3,3,-1,-1,-1,4,4,4,4,-1,-1,-1,-1,5,5,5,5,5,-1,-1,-1,
%T -1,-1,6,6,6,6,6,6,-1,-1,-1,-1,-1,-1,7,7,7,7,7,7,7,-1,-1,-1,-1,-1,-1,
%U -1,8,8,8,8,8,8,8,8,-1,-1,-1,-1,-1,-1,-1,-1,9,9,9,9,9,9,9,9,9,-1,-1,-1,-1,-1,-1,-1,-1,-1,10,10,10,10,10,10,10,10,10,10
%N Irregular triangle T(n,k) read by rows: n repetitions of -1 followed by (n+1) repetitions of n+1.
%C Row n has 2n+1 terms.
%e 1,
%e -1, 2, 2,
%e -1, -1, 3, 3, 3,
%e -1, -1, -1, 4, 4, 4, 4,
%e -1, -1, -1, -1, 5, 5, 5, 5, 5,
%e -1, -1, -1, -1, -1, 6, 6, 6, 6, 6, 6,
%e -1, -1, -1, -1, -1, -1, 7, 7, 7, 7, 7, 7, 7,
%e -1, -1, -1, -1, -1, -1, -1, 8, 8, 8, 8, 8, 8, 8, 8,
%e -1, -1, -1, -1, -1, -1, -1, -1, 9, 9, 9, 9, 9, 9, 9, 9, 9,
%e -1, -1, -1, -1, -1, -1, -1, -1, -1, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10
%t Flatten[Table[Join[PadRight[{},n,-1],PadRight[{},n+1,n+1]],{n,0,9}]] (* _Harvey P. Dale_, May 07 2014 *)
%Y Cf. A002061 (row sums).
%K sign,tabf,easy
%O 0,3
%A _Paul Curtz_, Jun 16 2008