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 A188406 #10 Apr 07 2020 15:25:55 %S A188406 1,1,6,69,1620,62781,3710272,313568636,36218801244,5518184697792, %T A188406 1078258692423672,264082675302603684,79537577428138854144, %U A188406 28988656113108616134732,12610397520409429024276176,6469939930732195901177163384,3874562148530193751600746715440,2683567291732998871830525552934800 %N A188406 Number of (5*n) X n binary arrays with rows in nonincreasing order, 5 ones in every column and no more than 2 ones in any row. %C A188406 Number of n X n symmetric matrices with nonnegative integer entries and all row and column sums 5. - _Andrew Howroyd_, Apr 07 2020 %e A188406 All solutions for 10X2 %e A188406 ..1..1....1..1....1..1....1..1....1..0....1..1 %e A188406 ..1..1....1..0....1..1....1..1....1..0....1..1 %e A188406 ..1..1....1..0....1..1....1..0....1..0....1..1 %e A188406 ..1..1....1..0....1..1....1..0....1..0....1..0 %e A188406 ..1..0....1..0....1..1....1..0....1..0....1..0 %e A188406 ..0..1....0..1....0..0....0..1....0..1....0..1 %e A188406 ..0..0....0..1....0..0....0..1....0..1....0..1 %e A188406 ..0..0....0..1....0..0....0..1....0..1....0..0 %e A188406 ..0..0....0..1....0..0....0..0....0..1....0..0 %e A188406 ..0..0....0..0....0..0....0..0....0..1....0..0 %Y A188406 Row 5 of A188403. %K A188406 nonn %O A188406 0,3 %A A188406 _R. H. Hardin_, Mar 30 2011 %E A188406 a(0)=1 prepended and terms a(10) and beyond from _Andrew Howroyd_, Apr 07 2020