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 A224313 #6 Jul 23 2025 05:06:03 %S A224313 243,11664,82700,345875,1258372,4420701,15312504,51743213,168153223, %T A224313 520664883,1530227559,4268724974,11327557052,28687337144,69591692782, %U A224313 162311418316,365262043261,795700321817,1682982694668,3465433571507 %N A224313 Number of 5Xn 0..2 arrays with diagonals and rows unimodal and antidiagonals nondecreasing. %C A224313 Row 5 of A224310 %H A224313 R. H. Hardin, <a href="/A224313/b224313.txt">Table of n, a(n) for n = 1..210</a> %F A224313 Empirical: a(n) = (1/1379196149760000)*n^20 - (1/137919614976000)*n^19 + (41/33874993152000)*n^18 + (1/426995712000)*n^17 + (88069/104613949440000)*n^16 + (102569/10461394944000)*n^15 + (1648459/2988969984000)*n^14 + (8052547/1494484992000)*n^13 + (615490013/2299207680000)*n^12 - (886807741/229920768000)*n^11 + (219072974333/3218890752000)*n^10 - (466264670551/1609445376000)*n^9 - (4824912304573/2490808320000)*n^8 + (350881754231/4981616640)*n^7 - (289916128775839/373621248000)*n^6 + (131084442677207/20756736000)*n^5 - (232251293325755159/6175128960000)*n^4 + (1510872624234341/8576568000)*n^3 - (2770659376747739/4655851200)*n^2 + (405320158706/285285)*n - 1873744 for n>9 %e A224313 Some solutions for n=3 %e A224313 ..0..0..2....2..2..0....0..1..0....2..1..0....0..0..0....1..1..0....1..1..1 %e A224313 ..0..2..0....2..2..0....1..0..0....1..2..0....0..2..1....1..1..1....2..2..0 %e A224313 ..2..1..0....2..1..1....2..2..2....2..1..1....2..1..1....1..1..0....2..0..0 %e A224313 ..1..1..1....2..1..1....2..2..2....2..1..0....2..2..0....1..1..0....0..2..0 %e A224313 ..2..1..1....2..2..0....2..2..0....1..0..0....2..1..0....1..1..1....2..2..2 %K A224313 nonn %O A224313 1,1 %A A224313 _R. H. Hardin_ Apr 03 2013