cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A030254 Number of nonisomorphic groupoids with 1 idempotent and a nontrivial symmetry.

Original entry on oeis.org

0, 0, 54, 12664
Offset: 1

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Crossrefs

Column k=1 of A038020.

Formula

a(n) = A030253(n) - A030271(n).

Extensions

a(3) corrected by Andrew Howroyd, Feb 02 2023