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.
%I A212845 #17 Sep 10 2019 19:03:36 %S A212845 1,3,163,271375,21855093749 %N A212845 Erroneous version of A212806. %C A212845 Included in accordance with OEIS policy of listing published but incorrect sequences, with pointers to the correct versions. %H A212845 Morton Abramson and David Promislow, <a href="https://doi.org/10.1016/0097-3165(78)90012-2">Enumeration of arrays by column rises</a>, J. Combinatorial Theory Ser. A 24(2) (1978), 247--250. MR0469773 (57 #9554); see p. 250. %K A212845 dead %O A212845 1,2