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 A223802 #6 Jul 23 2025 04:32:22 %S A223802 64,4096,110116,1658703,16979881,131295500,818316500,4293683039, %T A223802 19561009057,79169569680,289707943960,971844411710,3021916484046, %U A223802 8789182733640,24090737306249,62620436201529,155188103218258 %N A223802 Number of 3Xn 0..3 arrays with rows and antidiagonals unimodal. %C A223802 Row 3 of A223801 %H A223802 R. H. Hardin, <a href="/A223802/b223802.txt">Table of n, a(n) for n = 1..210</a> %F A223802 Empirical: a(n) = (89/169374965760)*n^18 + (811/30536352000)*n^17 + (94651/130767436800)*n^16 + (32953/2554051500)*n^15 + (353321/2134978560)*n^14 + (42487607/26687232000)*n^13 + (2427919/205286400)*n^12 + (329331899/4790016000)*n^11 + (2304632003/7315660800)*n^10 + (10342060619/9144576000)*n^9 + (4533016361/1437004800)*n^8 + (13748687149/2052864000)*n^7 + (50457321263/4670265600)*n^6 + (22295176297/1796256000)*n^5 + (1377479947/136216080)*n^4 + (30053444821/9081072000)*n^3 + (2978057767/367567200)*n^2 + (16725/2431)*n + 1 %e A223802 Some solutions for n=3 %e A223802 ..2..2..0....2..3..3....3..1..0....2..0..0....0..3..1....2..1..0....1..2..2 %e A223802 ..3..1..0....2..2..1....2..1..1....0..0..3....3..2..1....1..3..1....1..2..0 %e A223802 ..1..1..3....1..2..0....3..3..0....1..3..1....2..2..0....1..3..1....3..1..0 %K A223802 nonn %O A223802 1,1 %A A223802 _R. H. Hardin_ Mar 27 2013