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 A363881 #35 Jul 17 2023 11:01:59 %S A363881 1,0,0,1,3,13,50,230,1110,5787,32335,191950,1206247,7997702,55733468, %T A363881 406952888,3105706421,24710573792,204547052598,1758110677909, %U A363881 15663244043627,144412976181189,1375896762258868,13528184875421816,137098357090429007,1430440534060723253 %N A363881 Number of partitions of [n] such that no block contains its size as an element. %H A363881 Wikipedia, <a href="https://en.wikipedia.org/wiki/Partition_of_a_set">Partition of a set</a> %e A363881 a(0) = 1: () the empty partition. %e A363881 a(3) = 1: 13|2. %e A363881 a(4) = 3: 124|3, 13|2|4, 14|2|3. %e A363881 a(5) = 13: 1235|4, 124|35, 124|3|5, 125|34, 125|3|4, 13|245, 13|2|45, 13|2|4|5, 145|2|3, 14|2|35, 14|2|3|5, 15|2|34, 15|2|3|4. %e A363881 a(6) = 50: 12346|5, 1235|46, 1235|4|6, 1236|45, ..., 15|2|3|4|6, 16|2|35|4, 16|2|3|45, 16|2|3|4|5. %Y A363881 Cf. A000110, A326493, A364277. %K A363881 nonn %O A363881 0,5 %A A363881 _Alois P. Heinz_, Jul 17 2023