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A159800 Triangle read by rows in which row n contains a finite triangle as shown below. 5
1, 1, 2, 2, 2, 3, 2, 1, 2, 2, 1, 1, 2, 2, 3, 3, 3, 3, 4, 4, 3, 3, 4, 5, 4, 3, 2, 3, 4, 4, 3, 2, 1, 2, 3, 3, 3, 2, 1, 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 4, 5, 5, 5, 4, 4, 5, 6, 6, 5, 4, 4, 5, 6, 7, 6, 5, 4, 3, 4, 5, 6, 6, 5, 4, 3, 2, 3, 4, 5, 5, 5, 4, 3, 2, 1, 2, 3, 4, 4, 4, 4, 3, 2, 1, 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..105.

EXAMPLE

The main triangle begins:

1,

1,2,2,2,3,2,1,2,2,1,

1,2,2,3,3,3,3,4,4,3,3,4,5,4,3,2,3,4,4,3,2,1,2,3,3,3,2,1,

1,2,2,3,3,3,4,4,4,4,4,5,5,5,4,4,5,6,6,5,4,4,5,6,7,6,5,4,3,4,5,6,6,5,4,3,...

In which row 1 contains a vertex, only:

1

Row 2 contains the triangle:

1

2,2

2,3,2

1,2,2,1

Row 3 contains the triangle:

1

2,2

3,3,3

3,4,4,3

3,4,5,4,3

2,3,4,4,3,2

1,2,3,3,3,2,1

Row 4 contains the triangle:

1

2,2

3,3,3

4,4,4,4

4,5,5,5,4

4,5,6,6,5,4

4,5,6,7,6,5,4

3,4,5,6,6,5,4,3

2,3,4,5,5,5,4,3,2

1,2,3,4,4,4,4,3,2,1

Row 5 contains the triangle:

1

2,2

3,3,3

4,4,4,4

5,5,5,5,5

5,6,6,6,6,5

5,6,7,7,7,6,5

5,6,7,8,8,7,6,5

5,6,7,8,9,8,7,6,5

4,5,6,7,8,8,7,6,5,4

3,4,5,6,7,7,7,6,5,4,3

2,3,4,5,6,6,6,6,5,4,3,2

1,2,3,4,5,5,5,5,5,4,3,2,1

And so on...

CROSSREFS

Sequence in context: A014843 A116987 A219838 * A273021 A071137 A193990

Adjacent sequences:  A159797 A159798 A159799 * A159801 A159802 A159803

KEYWORD

easy,nonn,tabf

AUTHOR

Omar E. Pol, Nov 09 2009

STATUS

approved

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Last modified December 11 04:29 EST 2018. Contains 318049 sequences. (Running on oeis4.)