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 A268260 #4 Jan 29 2016 12:47:13 %S A268260 57,407,2907,20771,148468,1061632,7594224,54345509,389060724, %T A268260 2786424182,19964380499,143102062257,1026171833136,7361751375225, %U A268260 52836226761762,379380311345241,2725291071400498,19586141747713834,140826889434423348 %N A268260 Number of length-(n+1) 0..7 arrays with new repeated values introduced in sequential order starting with zero. %C A268260 Column 7 of A268261. %H A268260 R. H. Hardin, <a href="/A268260/b268260.txt">Table of n, a(n) for n = 1..210</a> %F A268260 Empirical: a(n) = 57*a(n-1) -1400*a(n-2) +19187*a(n-3) -157759*a(n-4) +765212*a(n-5) -1872339*a(n-6) +503475*a(n-7) +6299972*a(n-8) -2706851*a(n-9) -14207501*a(n-10) -11689832*a(n-11) -4172972*a(n-12) -680688*a(n-13) -40320*a(n-14) %e A268260 Some solutions for n=5 %e A268260 ..6....7....3....1....6....4....1....5....1....2....7....0....5....5....1....4 %e A268260 ..0....3....1....2....1....0....4....0....4....1....0....0....2....0....4....2 %e A268260 ..2....4....3....6....2....4....1....4....0....3....3....0....3....3....6....0 %e A268260 ..3....0....5....4....7....7....5....1....2....4....4....7....7....1....0....5 %e A268260 ..7....0....7....0....6....2....4....7....5....0....7....2....5....4....7....1 %e A268260 ..6....6....6....5....5....6....5....5....0....5....2....4....7....6....2....6 %Y A268260 Cf. A268261. %K A268260 nonn %O A268260 1,1 %A A268260 _R. H. Hardin_, Jan 29 2016