A171176 Triangle read by rows in which row n lists 3n-1 together with the first 2n-1 positive integers, in reverse order.

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.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

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;

Mathematica

Table[{3n-1, Reverse[Range[2n-1]]}, {n, 10}]//Flatten (* Harvey P. Dale, Jun 26 2022 *)

Crossrefs

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

Cf. A132209 (row sums). - R. J. Mathar, Mar 01 2010

Sequence in context: A143409 A197387 A171177 * A332529 A213849 A067418

Adjacent sequences: A171173 A171174 A171175 * A171177 A171178 A171179

Keyword

easy,nonn,tabf

Author

Omar E. Pol, Feb 23 2010

Status

approved