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 A224357 #6 Jul 23 2025 05:07:11 %S A224357 729,46656,349280,1351748,4231138,12340932,34697869,94262290, %T A224357 246254814,616242552,1475123504,3379586703,7423803582,15672970622, %U A224357 31884279651,62668814332,119312143790,220555944774,396752366132,695942226325 %N A224357 Number of 6Xn 0..2 arrays with diagonals and antidiagonals unimodal and rows nondecreasing. %C A224357 Row 6 of A224353 %H A224357 R. H. Hardin, <a href="/A224357/b224357.txt">Table of n, a(n) for n = 1..210</a> %F A224357 Empirical: a(n) = (761/8553600)*n^12 + (1733/3326400)*n^11 + (1459/108864)*n^10 + (4187/40320)*n^9 + (1551227/1814400)*n^8 + (72841/12600)*n^7 + (1802801/19440)*n^6 - (66259339/120960)*n^5 + (9020552353/1360800)*n^4 - (817656577/50400)*n^3 + (5508355001/83160)*n^2 - (57456263/1540)*n - 269256 for n>7 %e A224357 Some solutions for n=3 %e A224357 ..0..0..0....0..0..0....0..0..0....0..0..0....0..0..2....0..0..2....0..0..1 %e A224357 ..2..2..2....1..2..2....0..1..2....0..0..0....0..0..2....1..1..1....0..1..2 %e A224357 ..0..1..2....0..1..1....1..1..2....0..0..1....0..2..2....0..1..1....0..2..2 %e A224357 ..0..0..1....1..2..2....0..1..1....0..2..2....0..0..2....1..1..1....1..2..2 %e A224357 ..0..0..1....2..2..2....1..1..1....0..2..2....0..1..2....1..1..2....0..2..2 %e A224357 ..0..0..1....1..2..2....0..2..2....2..2..2....0..0..0....0..1..2....1..1..1 %K A224357 nonn %O A224357 1,1 %A A224357 _R. H. Hardin_ Apr 04 2013