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 A223739 #6 Jul 23 2025 04:26:32 %S A223739 86,7396,237088,3868968,41586328,340038574,2289596121,13281578167, %T A223739 68222609208,316008418514,1337293881157,5222063556941,18967899632349, %U A223739 64513878383831,206644044321249,626458582331341,1805406612393872 %N A223739 Number of nX5 0..2 arrays with rows, columns, diagonals and antidiagonals unimodal. %C A223739 Column 5 of A223742 %H A223739 R. H. Hardin, <a href="/A223739/b223739.txt">Table of n, a(n) for n = 1..136</a> %F A223739 Empirical: a(n) = (63370093/405483668029440000)*n^20 - (268330757/121645100408832000)*n^19 + (13774799/121949975347200)*n^18 - (2424889373/2134124568576000)*n^17 + (18925169/1107025920000)*n^16 + (11462071/62705664000)*n^15 - (29544684331/5021469573120)*n^14 + (20545808232973/188305108992000)*n^13 - (12540957049199/13795246080000)*n^12 + (41582497189459/9656672256000)*n^11 - (2781361848649/61312204800)*n^10 + (2584592276085773/1379524608000)*n^9 - (6240419528063566523/156920924160000)*n^8 + (23876233435912776007/47076277248000)*n^7 - (1929147516259295957/448345497600)*n^6 + (5962644577920598223/237758976000)*n^5 - (66236190322655654183/661620960000)*n^4 + (14575286592197809/53856000)*n^3 - (12552295491184305071/24443218800)*n^2 + (15114021973648951/19399380)*n - 808791295 for n>11 %e A223739 Some solutions for n=3 %e A223739 ..0..0..2..0..0....0..0..1..2..2....0..0..1..2..0....0..0..1..1..1 %e A223739 ..0..0..2..2..2....1..2..2..2..0....0..0..2..2..2....0..0..2..1..0 %e A223739 ..0..1..2..1..1....1..1..2..0..0....0..0..0..1..1....0..0..2..0..0 %K A223739 nonn %O A223739 1,1 %A A223739 _R. H. Hardin_ Mar 26 2013