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 A305783 #5 Jun 10 2018 13:31:30 %S A305783 1,9,61,359,2071,11521,64536,351890,1937292,10385051,56327364, %T A305783 297361209,1592259558,8294350334,43929021137,226237017737, %U A305783 1187116072881,6055309005874,31524381075907,159529143743414,825010507438945,4148043681253075,21331478060780614 %N A305783 Number of set partitions of [n] with alternating parity of elements and exactly nine blocks. %H A305783 Wikipedia, <a href="https://en.wikipedia.org/wiki/Partition_of_a_set">Partition of a set</a> %Y A305783 Column k=9 of A274581. %K A305783 nonn %O A305783 9,2 %A A305783 _Alois P. Heinz_, Jun 10 2018