A222173 Number of pentagons added at n-th stage to the structure of A222172.

0, 1, 1, 1, 2, 3, 2, 1, 2, 4, 4, 3, 5, 7, 4, 1, 2, 4, 6, 8

Offset: 0

Author

Omar E. Pol, Mar 21 2013

Keywords

• nonn
• tabf
• more

Comments

Essentially the first differences of A222172.

Also number of P-toothpicks added at n-th stage to the P-toothpick structure of A222172.

First differs from A152978 at a(9).

Examples

			Apparently this is an irregular triangle:
0;
1, 1;
1, 2, 3, 2;
1, 2, 4, 4, 3, 5, 7, 4;
1, 2, 4, 6, 8,...
		

Links

• N. J. A. Sloane, Catalog of Toothpick and Cellular Automata Sequences in the OEIS
• Index entries for sequences related to toothpick sequences

Crossrefs

Cf. A139251, A152978, A222172, A222177, A222180, A222181.

Formula

a(n) = A222181(n+2)/10 = A222177(n+1)/2, n >= 1.