A049340 Triangle read by rows: T(n,k) is the number of planar graphs with n >= 1 nodes and 0 <= k <= binomial(n,2) edges, all degrees even.

1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 1, 1, 3, 2, 2, 1, 1, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 1, 3, 4, 4, 6, 5, 5, 3, 2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 1, 1, 3, 4, 7, 9, 15, 17, 22, 14, 16, 5, 4, 0, 1, 0, 0, 0

Offset: 1

Author

Brendan McKay

Keywords

• nonn
• tabf
• easy
• nice

Examples

			Triangle begins:
  1;
  1, 0;
  1, 0, 0, 1;
  1, 0, 0, 1, 1, 0, 0;
  1, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0;
  1, 0, 0, 1, 1, 1, 3, 2, 2, 1, 1, 0, 1, 0, 0, 0;
  ...
		

Links

• Sean A. Irvine, Table of n, a(n) for n = 1..231, rows 1..11 flattened
• Sean A. Irvine, Java program (github)

Crossrefs

Rows sums give A049339.

Cf. A000944, A021103, A003094, A049334.

Extensions

Entry revised by Sean A. Irvine, Jul 29 2021