

A124171


Sequence obtained by reading the triangles shown below by rows.


2



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, 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, 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
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OFFSET

1,3


COMMENTS

It appears that this is also a triangle read by rows in which row n lists the first A000217(n) positive integers, n >= 1 (see example, second part).  Omar E. Pol, May 29 2012


LINKS

Table of n, a(n) for n=1..87.


EXAMPLE

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 14 15
From Omar E. Pol, May 29 2012: (Start)
Written as an irregular triangle the sequence begins:
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, 14, 15;
Row n has length A000217(n). (End)


MAPLE

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, May 18 2007


CROSSREFS

See A115215 for another version.
Sequence in context: A194107 A071797 A025481 * A276146 A210530 A076645
Adjacent sequences: A124168 A124169 A124170 * A124172 A124173 A124174


KEYWORD

nonn,tabf,easy


AUTHOR

Colm Mulcahy, Dec 05 2006


EXTENSIONS

More terms from R. J. Mathar, May 18 2007


STATUS

approved



