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 A269436 #8 Jan 22 2019 07:46:26 %S A269436 15,78,250,615,1281,2380,4068,6525,9955,14586,20670,28483,38325,50520, %T A269436 65416,83385,104823,130150,159810,194271,234025,279588,331500,390325, %U A269436 456651,531090,614278,706875,809565,923056,1048080,1185393,1335775 %N A269436 Number of length-4 0..n arrays with no repeated value greater than the previous repeated value. %H A269436 R. H. Hardin, <a href="/A269436/b269436.txt">Table of n, a(n) for n = 1..210</a> %F A269436 Empirical: a(n) = n^4 + 4*n^3 + (11/2)*n^2 + (7/2)*n + 1. %F A269436 Conjectures from _Colin Barker_, Jan 22 2019: (Start) %F A269436 G.f.: x*(15 + 3*x + 10*x^2 - 5*x^3 + x^4) / (1 - x)^5. %F A269436 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 A269436 (End) %e A269436 Some solutions for n=8: %e A269436 ..7. .8. .1. .4. .8. .5. .6. .6. .7. .0. .7. .7. .8. .5. .5. .0 %e A269436 ..6. .3. .6. .3. .5. .3. .2. .4. .2. .7. .6. .1. .3. .3. .7. .3 %e A269436 ..3. .8. .5. .0. .4. .7. .2. .7. .4. .7. .7. .2. .5. .0. .2. .4 %e A269436 ..7. .2. .7. .0. .2. .1. .3. .4. .0. .8. .4. .6. .5. .0. .8. .1 %Y A269436 Row 4 of A269435. %K A269436 nonn %O A269436 1,1 %A A269436 _R. H. Hardin_, Feb 26 2016