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 A269410 #7 Jan 21 2019 10:06:51 %S A269410 9,63,222,570,1215,2289,3948,6372,9765,14355,20394,28158,37947,50085, %T A269410 64920,82824,104193,129447,159030,193410,233079,278553,330372,389100, %U A269410 455325,529659,612738,705222,807795,921165,1046064,1183248,1333497 %N A269410 Number of length-4 0..n arrays with no repeated value greater than or equal to the previous repeated value. %H A269410 R. H. Hardin, <a href="/A269410/b269410.txt">Table of n, a(n) for n = 1..210</a> %F A269410 Empirical: a(n) = n^4 + 4*n^3 + (7/2)*n^2 + (1/2)*n. %F A269410 Conjectures from _Colin Barker_, Jan 21 2019: (Start) %F A269410 G.f.: 3*x*(3 + 6*x - x^2) / (1 - x)^5. %F A269410 a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5. %F A269410 (End) %e A269410 Some solutions for n=8: %e A269410 ..8. .3. .1. .0. .3. .0. .8. .2. .3. .1. .0. .4. .3. .5. .4. .6 %e A269410 ..8. .8. .3. .5. .4. .2. .1. .4. .0. .5. .2. .4. .0. .6. .4. .8 %e A269410 ..4. .7. .3. .8. .7. .2. .0. .5. .3. .3. .7. .0. .0. .1. .2. .0 %e A269410 ..0. .8. .8. .7. .5. .8. .5. .8. .2. .8. .0. .0. .2. .1. .4. .2 %Y A269410 Row 4 of A269409. %K A269410 nonn %O A269410 1,1 %A A269410 _R. H. Hardin_, Feb 25 2016