A212785 - OEIS

%I #6 May 27 2012 07:27:55

%S 13,162,1238,5104,16594,43727,101743,211461,408430,735896,1261599,

%T 2064329,3259612,4975687,7395946,10715635,15205983,21151890,28937100,

%U 38956477,51737361,67810309,87873466,112625630,142969752,179799242

%N Half the number of 0..n arrays of length 6 with second differences nonzero

%C Row 4 of A212782

%H R. H. Hardin, <a href="/A212785/b212785.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = a(n-2) +2*a(n-3) +2*a(n-4) -a(n-5) -2*a(n-6) -5*a(n-7) -3*a(n-8) +3*a(n-10) +6*a(n-11) +5*a(n-12) +3*a(n-13) -3*a(n-14) -5*a(n-15) -6*a(n-16) -3*a(n-17) +3*a(n-19) +5*a(n-20) +2*a(n-21) +a(n-22) -2*a(n-23) -2*a(n-24) -a(n-25) +a(n-27)

%e Some solutions for n=5

%e ..2....2....5....1....3....3....5....4....0....5....3....3....3....4....2....2

%e ..0....4....1....4....5....0....2....0....1....4....5....4....4....3....5....1

%e ..5....3....3....5....3....3....0....0....1....1....1....0....4....5....4....3

%e ..4....3....2....3....4....5....0....5....0....5....3....4....1....0....0....2

%e ..0....1....4....5....4....2....1....4....5....2....2....3....0....5....3....2

%e ..5....2....1....4....5....3....0....5....3....5....4....1....0....5....5....5

%K nonn

%O 1,1

%A _R. H. Hardin_ May 27 2012