

A171176


Triangle read by rows in which row n lists 3n1 together with the first 2n1 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
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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



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[{3n1, Reverse[Range[2n1]]}, {n, 10}]//Flatten (* Harvey P. Dale, Jun 26 2022 *)


CROSSREFS

Cf. A000027, A016789, A172310, A171164, A161165, A161166, A171172, A171173, A171174, A171175, A171177, A171178.


KEYWORD

easy,nonn,tabf


AUTHOR



STATUS

approved



