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A038036 Number of nonisomorphic and nonantiisomorphic rings with n elements. 1
1, 2, 2, 10, 2, 4, 2, 46, 10, 4, 2, 20, 2, 4, 4, 316, 2, 20, 2, 20, 4, 4, 2, 92, 10, 4, 53, 20, 2, 8, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Number of rings of order n, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the * operator). - Jianing Song, Oct 26 2019

LINKS

Table of n, a(n) for n=1..31.

FORMULA

a(n) = (A027623(n)+A037290(n))/2. - Jianing Song, Oct 26 2019

CROSSREFS

Cf. A027623, A037290.

Sequence in context: A019514 A135816 A157341 * A297793 A319880 A133631

Adjacent sequences:  A038033 A038034 A038035 * A038037 A038038 A038039

KEYWORD

nonn,hard,more

AUTHOR

Christian G. Bower, Jun 15 1998

EXTENSIONS

a(16)-a(31) added by Jianing Song, Oct 26 2019

STATUS

approved

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Last modified January 21 04:20 EST 2021. Contains 340332 sequences. (Running on oeis4.)