%I A124171
%S A124171 1,1,2,3,1,2,3,4,5,6,1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10,11,12,13,
%T A124171 14,15,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,1,2,3,4,5,
%U A124171 6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,1,2,
               3
%N A124171 Sequence obtained by reading the triangles shown below by rows.
%e A124171 1
%e A124171 1
%e A124171 2 3
%e A124171 1
%e A124171 2 3
%e A124171 4 5 6
%e A124171 1
%e A124171 2 3
%e A124171 4 5 6
%e A124171 7 8 9 10
%e A124171 1
%e A124171 2 3
%e A124171 4 5 6
%e A124171 7 8 9 10
%e A124171 11 12 13 14 15
%p A124171 A000217 := proc(n) n*(n+1)/2 ; end : for t from 1 to 10 do for i from 
               1 to A000217(t) do printf("%d, ",i) ; od ; od ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), 
               May 18 2007
%Y A124171 See A115215 for another version.
%Y A124171 Sequence in context: A003315 A071797 A025481 this_sequence A076645 A011448 
               A067280
%Y A124171 Adjacent sequences: A124168 A124169 A124170 this_sequence A124172 A124173 
               A124174
%K A124171 nonn,tabf,easy
%O A124171 1,3
%A A124171 Colm Mulcahy (colm(AT)spelman.edu), Dec 05 2006
%E A124171 More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 18 2007