A038036 Number of nonisomorphic and nonantiisomorphic rings with n elements.

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

Offset: 1

Author

Christian G. Bower, Jun 15 1998

Keywords

• nonn
• hard
• more

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

Crossrefs

Cf. A027623, A037290.

Formula

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

Extensions

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