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 A223803 #6 Jul 23 2025 04:32:27 %S A223803 256,65536,4816168,151310069,2844578252,37217420249,370255807510, %T A223803 2967702264487,19953618004020,115901407902175,594677748128499, %U A223803 2742258352954012,11522283571283326,44607717280309708,160585424830894289 %N A223803 Number of 4Xn 0..3 arrays with rows and antidiagonals unimodal. %C A223803 Row 4 of A223801 %H A223803 R. H. Hardin, <a href="/A223803/b223803.txt">Table of n, a(n) for n = 1..210</a> %F A223803 Empirical: a(n) = (1224989653/34469355651846635520000)*n^24 + (1274345773/470036667979726848000)*n^23 + (89684176061/749333818518405120000)*n^22 + (92332596599/25545471085854720000)*n^21 + (3678754549/45368802017280000)*n^20 + (80494587659/57244753133568000)*n^19 + (1442890795373/74694359900160000)*n^18 + (17944065812311/84031154887680000)*n^17 + (808497136964749/421803444142080000)*n^16 + (887979405310979/63270516621312000)*n^15 + (712542665498819/8497871585280000)*n^14 + (511835344841201/1255367393280000)*n^13 + (2484047083210032763/1546612628520960000)*n^12 + (29342532497594837/5751865147392000)*n^11 + (124717183755287231/9586441912320000)*n^10 + (524203224847641397/19772036444160000)*n^9 + (23382114961946647/547211427840000)*n^8 + (33110696329013011/640237370572800)*n^7 + (78034921690145238953/2128789257154560000)*n^6 - (394245218967404573/9855505820160000)*n^5 - (11421559789359613027/81307923016320000)*n^4 - (57003741297203/301945644000)*n^3 + (2875733400346871/11416863427200)*n^2 + (225454400125/1070845776)*n - 15 %e A223803 Some solutions for n=3 %e A223803 ..0..0..0....0..0..2....0..0..0....0..0..2....0..0..2....0..0..0....0..0..2 %e A223803 ..0..0..3....0..2..3....2..2..1....0..2..3....1..2..0....1..2..0....1..2..0 %e A223803 ..0..1..0....0..3..0....1..2..0....1..3..1....3..2..0....0..3..0....2..3..2 %e A223803 ..1..2..2....3..0..0....0..3..3....0..0..3....0..3..3....1..1..3....3..3..3 %K A223803 nonn %O A223803 1,1 %A A223803 _R. H. Hardin_ Mar 27 2013