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 A224017 #6 Jul 23 2025 04:51:58 %S A224017 2187,279936,4549684,32148473,157347899,630339756,2200064042, %T A224017 6905100668,19884396658,53273320570,134149069532,319991143494, %U A224017 727540081476,1584708043525,3320910477511,6719637130491,13169292526095,25065634112639 %N A224017 Number of 7Xn 0..2 arrays with rows nondecreasing and antidiagonals unimodal. %C A224017 Row 7 of A224012 %H A224017 R. H. Hardin, <a href="/A224017/b224017.txt">Table of n, a(n) for n = 1..210</a> %F A224017 Empirical: a(n) = (118519/21794572800)*n^14 + (93527/444787200)*n^13 + (611041/119750400)*n^12 + (20516659/239500800)*n^11 + (983303/907200)*n^10 + (76863193/7257600)*n^9 + (6226908251/76204800)*n^8 + (10267137467/21772800)*n^7 + (44655148529/21772800)*n^6 + (59149317869/10886400)*n^5 + (6745497467/1108800)*n^4 - (150827667029/9979200)*n^3 - (38880748217/10090080)*n^2 + (55017835997/360360)*n + 124353 for n>5 %e A224017 Some solutions for n=3 %e A224017 ..0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0....0..0..0 %e A224017 ..0..0..1....0..0..0....0..0..0....0..0..1....0..0..0....0..0..1....0..0..1 %e A224017 ..1..1..2....0..1..2....0..2..2....1..1..2....0..1..2....0..1..2....0..1..2 %e A224017 ..0..1..1....1..1..1....1..1..1....0..0..0....2..2..2....0..1..2....2..2..2 %e A224017 ..1..1..1....0..2..2....1..1..2....0..1..2....0..1..1....1..1..1....1..1..2 %e A224017 ..1..2..2....0..1..1....1..1..1....1..1..1....0..2..2....0..0..1....0..2..2 %e A224017 ..0..0..2....0..2..2....1..1..1....0..2..2....0..0..1....0..0..0....0..2..2 %K A224017 nonn %O A224017 1,1 %A A224017 _R. H. Hardin_ Mar 30 2013