A344260 a(n) is the number of relations from an n-element set into a set of at most n elements.

1, 3, 21, 585, 69905, 34636833, 69810262081, 567382630219905, 18519084246547628289, 2422583247133816584929793, 1268889750375080065623288448001, 2659754699919401766201267083003561985, 22306191045953951743035482794815064402563073, 748380193317489370459454048174977015562807531282433

Offset

0,2

Comments

Symmetrically, also the number of relations from a set of at most n elements into an n-element set.

Links

Table of n, a(n) for n=0..13.

Formula

a(n) = (2^(n+n^2) - 1)/(2^n - 1) for n > 0 and a(0) = 1.

a(n) ~ 2^(n^2).

a(n) = A275779(n) + 1. - Hugo Pfoertner, May 14 2021

Mathematica

Join[{1}, Table[(2^(n+n^2)-1)/(2^n-1), {n, 13}]]

Crossrefs

Row sums of A344110.

Cf. A000079, A002416, A031971, A089072, A117401, A275779.

Sequence in context: A014375 A135748 A145386 * A135327 A128679 A292331

Adjacent sequences: A344257 A344258 A344259 * A344261 A344262 A344263

Keyword

nonn

Author

Stefano Spezia, May 13 2021

Status

approved