cp's OEIS Frontend

A245875 Number of length 6+2 0..n arrays with some pair in every consecutive three terms totalling exactly n.

%I A245875 #7 Nov 04 2018 14:15:32
%S A245875 68,1281,4624,13961,30900,63241,113024,193137,305860,470321,688848,
%T A245875 987961,1369844,1869561,2488960,3272801,4222404,5393377,6786320,
%U A245875 8468841,10440628,12782441,15492864,18666961,22302020,26508561,31282384,36750617
%N A245875 Number of length 6+2 0..n arrays with some pair in every consecutive three terms totalling exactly n.
%H A245875 R. H. Hardin, <a href="/A245875/b245875.txt">Table of n, a(n) for n = 1..210</a>
%F A245875 Empirical: a(n) = 3*a(n-1) - 8*a(n-3) + 6*a(n-4) + 6*a(n-5) - 8*a(n-6) + 3*a(n-8) - a(n-9).
%F A245875 Conjectures from _Colin Barker_, Nov 04 2018: (Start)
%F A245875 G.f.: x*(68 + 1077*x + 781*x^2 + 633*x^3 - 1143*x^4 - 561*x^5 + 103*x^6 + 3*x^7 - x^8) / ((1 - x)^6*(1 + x)^3).
%F A245875 a(n) = 1 + 22*n + 31*n^2 + 77*n^3 + 29*n^4 + n^5 for n even.
%F A245875 a(n) = -5 - 44*n + 10*n^2 + 77*n^3 + 29*n^4 + n^5 for n odd.
%F A245875 (End)
%e A245875 Some solutions for n=8:
%e A245875 ..2....4....4....0....0....4....3....3....1....0....1....2....0....3....0....3
%e A245875 ..6....4....1....8....8....4....6....6....7....8....8....2....7....7....8....7
%e A245875 ..2....4....7....0....7....7....2....5....1....1....0....6....1....1....8....1
%e A245875 ..2....8....4....6....1....1....3....3....4....7....2....2....3....1....0....0
%e A245875 ..6....0....4....2....6....7....5....8....4....6....6....3....5....7....6....8
%e A245875 ..5....3....4....6....2....1....5....0....5....1....3....5....3....3....2....8
%e A245875 ..2....5....7....3....1....3....3....8....4....7....5....5....5....5....5....0
%e A245875 ..6....4....1....2....6....5....4....0....3....4....7....3....3....5....3....5
%Y A245875 Row 6 of A245869.
%K A245875 nonn
%O A245875 1,1
%A A245875 _R. H. Hardin_, Aug 04 2014