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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified November 14 02:19 EST 2019. Contains 329108 sequences. (Running on oeis4.)