A308557 Number of connected ungraceful graphs on n nodes.

0, 0, 0, 0, 3, 6, 34, 148, 1505, 29840

Offset

1,5

Links

Table of n, a(n) for n=1..10.

Eric Weisstein's World of Mathematics, Graceful Graph

Formula

a(n) = A001349(n) - A308549(n). - Pontus von Brömssen, Dec 29 2024

Crossrefs

Cf. A001349, A308549, A308556 (not necessarily connected ungraceful graphs).

Sequence in context: A186750 A203715 A249875 * A134748 A068904 A309774

Adjacent sequences: A308554 A308555 A308556 * A308558 A308559 A308560

Keyword

nonn,more,hard

Author

Eric W. Weisstein, Jun 07 2019

Extensions

a(8) from Eric W. Weisstein, Aug 16 2019

a(9) from Eric W. Weisstein, Nov 11 2025

a(10) from Eric W. Weisstein, Feb 27 2026

Status

approved