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 A223845 #6 Jul 23 2025 04:35:10 %S A223845 50,2500,64660,1006318,10804883,87613063,570145144,3107412546, %T A223845 14632983606,60951077586,228682697934,784020062496,2484771896660, %U A223845 7348846431262,20442258040721,53835488429681,134975315832464 %N A223845 Number of nX3 0..3 arrays with rows and columns unimodal. %C A223845 Column 3 of A223850 %H A223845 R. H. Hardin, <a href="/A223845/b223845.txt">Table of n, a(n) for n = 1..210</a> %F A223845 Empirical: a(n) = (89/169374965760)*n^18 + (811/30536352000)*n^17 + (2373533/3487131648000)*n^16 + (699851/62270208000)*n^15 + (11519407/87178291200)*n^14 + (51637/44352000)*n^13 + (7243453/912384000)*n^12 + (306562541/7185024000)*n^11 + (148370021/812851200)*n^10 + (33909163/54432000)*n^9 + (455467827113/268240896000)*n^8 + (5892168577/1596672000)*n^7 + (80009607001/12454041600)*n^6 + (31958071429/3592512000)*n^5 + (2175260234977/217945728000)*n^4 + (5539161569/648648000)*n^3 + (6387435643/1029188160)*n^2 + (637969/235620)*n + 1 %e A223845 Some solutions for n=3 %e A223845 ..3..0..0....1..0..0....0..1..0....3..1..0....1..2..1....0..0..3....2..3..2 %e A223845 ..3..3..2....1..3..2....3..3..3....3..2..1....0..2..3....2..2..1....0..3..2 %e A223845 ..3..2..1....3..1..1....0..2..2....0..1..3....0..3..3....3..1..0....0..2..3 %K A223845 nonn %O A223845 1,1 %A A223845 _R. H. Hardin_ Mar 27 2013