

A037291


Number of rings with 1 containing n elements.


7



1, 1, 1, 4, 1, 1, 1, 11, 4, 1, 1, 4, 1, 1, 1, 50, 1, 4, 1, 4, 1, 1, 1, 11, 4, 1, 12, 4, 1, 1, 1, 208, 1, 1, 1, 16, 1, 1, 1, 11, 1, 1, 1, 4, 4, 1, 1, 50, 4, 4, 1, 4, 1, 11, 1, 11, 1, 1, 1, 4, 1, 1, 4
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OFFSET

1,4


COMMENTS

Many authors simply call these "rings". They are also known as unital rings, rings with unity, or rings with identity.  Charles R Greathouse IV, Aug 12 2015


LINKS

Table of n, a(n) for n=1..63.
C. Noebauer, Home page [Archived copy as of 2008 from web.archive.org]


CROSSREFS

Cf. A027623, A037221.
Sequence in context: A184729 A127707 A113196 * A222317 A063851 A124777
Adjacent sequences: A037288 A037289 A037290 * A037292 A037293 A037294


KEYWORD

nonn,nice,hard


AUTHOR

Christian G. Bower, Jun 15 1998.


EXTENSIONS

a(16) and a(32)a(63) from Christof Noebauer (christof.noebauer(AT)algebra.unilinz.ac.at), Sep 29, 2000


STATUS

approved



