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 A223930 #6 Jul 23 2025 04:39:50 %S A223930 86,1915,15791,86439,386495,1548633,5773556,20277077,67308910, %T A223930 211460339,629882429,1783655626,4817110825,12451066977,30910052731, %U A223930 73949198559,171030335166,383497912713,835834876572,1774757616717,3678712344867 %N A223930 Number of nX5 0..2 arrays with rows, columns and antidiagonals unimodal and diagonals nondecreasing. %C A223930 Column 5 of A223933 %H A223930 R. H. Hardin, <a href="/A223930/b223930.txt">Table of n, a(n) for n = 1..210</a> %F A223930 Empirical: a(n) = (1/1379196149760000)*n^20 - (1/137919614976000)*n^19 + (331/304874938368000)*n^18 - (23/25406244864000)*n^17 + (22273/34871316480000)*n^16 + (2693/697426329600)*n^15 + (709123/2324754432000)*n^14 + (25469/53374464000)*n^13 + (818015239/6897623040000)*n^12 - (447002537/229920768000)*n^11 + (49691417869/1072963584000)*n^10 - (162095712841/268240896000)*n^9 + (48214267849049/6538371840000)*n^8 - (12967593924557/186810624000)*n^7 + (659685543839627/1120863744000)*n^6 - (379579885964341/93405312000)*n^5 + (71087813774265133/3087564480000)*n^4 - (15162068319635473/154378224000)*n^3 + (1768745631701119/6110804700)*n^2 - (6674903392214/14549535)*n + 130847 for n>9 %e A223930 Some solutions for n=3 %e A223930 ..0..1..1..1..2....0..1..0..0..0....0..2..2..2..2....0..1..1..1..0 %e A223930 ..1..1..1..1..1....1..2..2..1..1....0..1..2..2..2....1..1..1..1..1 %e A223930 ..1..1..1..2..1....2..2..2..2..2....0..0..2..2..2....1..1..1..1..2 %K A223930 nonn %O A223930 1,1 %A A223930 _R. H. Hardin_ Mar 29 2013