A020955 a(n) = n^(2^n - n - 1).

1, 1, 2, 81, 4194304, 1490116119384765625, 226267027688376192080197927193400943822503936, 258086210989349276047917817413172383631691140276099547911280598425927853437317437263620645695945672001

Offset: 0

Author

Yasutoshi Kohmoto

Keywords

• nonn

Comments

Number of finite models of natural number on the free class with n members.

Examples

			For n=2, a(2)=2, universe class={0,1}.
1 : { }ma 0, {0}ma 1, {0,1}ma 1, {1}ma 0,
2 : { }ma 0, {0}ma 1, {0,1}ma 1, {1}ma 1.
		

Links

• Yasutoshi Kohmoto, The Other Side of Mathematics [broken link?]
• Yasutoshi Kohmoto, The Other Side of Mathematics [via Internet Archive Wayback-machine]

Crossrefs

Cf. A097547.

Formula

a(n) = A097547(n)/A007778(n), n > 0. - R. J. Mathar, Jan 12 2017

Extensions

a(0)=1 and a(7) corrected by Vincenzo Librandi, Apr 25 2011