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A171176 Triangle read by rows in which row n lists 3n-1 together with the first 2n-1 positive integers, in reverse order. 10
2, 1, 5, 3, 2, 1, 8, 5, 4, 3, 2, 1, 11, 7, 6, 5, 4, 3, 2, 1, 14, 9, 8, 7, 6, 5, 4, 3, 2, 1, 17, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 20, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 23, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 26, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
a(n) is also the length of the n-th L-toothpick added to the structure of A171166.
LINKS
EXAMPLE
Triangle begins:
2, 1;
5, 3, 2, 1;
8, 5, 4, 3, 2, 1;
11, 7, 6, 5, 4, 3, 2, 1;
14, 9, 8, 7, 6, 5, 4, 3, 2, 1;
17, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1;
20, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1;
23, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1;
26, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1;
MATHEMATICA
Table[{3n-1, Reverse[Range[2n-1]]}, {n, 10}]//Flatten (* Harvey P. Dale, Jun 26 2022 *)
CROSSREFS
Cf. A132209 (row sums). - R. J. Mathar, Mar 01 2010
Sequence in context: A143409 A197387 A171177 * A332529 A213849 A067418
KEYWORD
easy,nonn,tabf
AUTHOR
Omar E. Pol, Feb 23 2010
STATUS
approved

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Last modified June 19 20:39 EDT 2024. Contains 373507 sequences. (Running on oeis4.)