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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
OFFSET
1,1
COMMENTS
a(n) is also the length of the n-th L-toothpick added to the structure of A171166.
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
KEYWORD
easy,nonn,tabf
AUTHOR
Omar E. Pol, Feb 23 2010
STATUS
approved