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A020955 a(n) = n^(2^n - n - 1). 1
1, 1, 2, 81, 4194304, 1490116119384765625, 226267027688376192080197927193400943822503936, 258086210989349276047917817413172383631691140276099547911280598425927853437317437263620645695945672001 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

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

LINKS

Table of n, a(n) for n=0..7.

Yasutoshi Kohmoto, The Other Side of Mathematics [broken link?]

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

FORMULA

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

EXAMPLE

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.

CROSSREFS

Cf. A097547.

Sequence in context: A123177 A209585 A090603 * A230398 A120826 A259308

Adjacent sequences:  A020952 A020953 A020954 * A020956 A020957 A020958

KEYWORD

nonn

AUTHOR

Yasutoshi Kohmoto

EXTENSIONS

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

STATUS

approved

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Last modified February 22 23:44 EST 2020. Contains 332157 sequences. (Running on oeis4.)