

A171176


Triangle read by rows in which row n lists 3n1 together with the first 2n1 positive integers, in reverse order.


9



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
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OFFSET

1,1


COMMENTS

a(n) is also the length of the nth Ltoothpick added to the structure of A171166.


LINKS

Table of n, a(n) for n=1..90.
N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS
Index entries for sequences related to toothpick sequences


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;


CROSSREFS

Cf. A000027, A016789, A172310, A171164, A161165, A161166, A171172, A171173, A171174, A171175, A171177, A171178.
Cf. A132209 (row sums). [From R. J. Mathar, Mar 01 2010]
Sequence in context: A143409 A197387 A171177 * A213849 A067418 A287548
Adjacent sequences: A171173 A171174 A171175 * A171177 A171178 A171179


KEYWORD

easy,nonn,tabf


AUTHOR

Omar E. Pol, Feb 23 2010


STATUS

approved



