1,2

a(9) >= 1491840 (K_1,1,7).

Table of graphs achieving these maxima:

1: K_1

2: K_2 = P_2

3: K_3 = C_3 = K_1,1,1

4: K_4

5: K_1,1,3

6: K_1,1,4

7: K_1,1,5

8: K_1,1,6

a(4) fails to correspond to the diamond graph K_1,1,2 since K_4 has 48 graceful labelings, while K_1,1,2 has only 32.

Table of n, a(n) for n=1..8.

Cf. A334307, A339892.

Sequence in context: A048501 A001815 A347324 * A052569 A221663 A232663

Adjacent sequences: A333725 A333726 A333727 * A333729 A333730 A333731

nonn,more

Eric W. Weisstein, Apr 03 2020

a(8) from Eric W. Weisstein, Jul 30 2020

approved