A249706 Number of length n+3 0..7 arrays with every four consecutive terms having the maximum of some two terms equal to the minimum of the remaining two terms.

904, 2864, 8688, 24032, 57912, 156416, 442144, 1235840, 3295784, 8902160, 24576568, 68205968, 186882480, 511124496, 1407327072, 3893357456, 10747255576, 29617387520, 81753189024, 226221330256, 626221254528, 1732751390816

Offset: 1

Author

R. H. Hardin, Nov 04 2014

Keywords

• nonn

Comments

Column 7 of A249707.

Examples

			Some solutions for n=6
..4....2....6....1....4....4....1....0....2....2....4....2....4....4....6....4
..3....0....3....7....4....3....2....1....6....0....1....0....3....3....3....6
..0....2....3....4....3....5....2....1....6....3....1....2....3....0....6....5
..3....2....3....4....7....4....3....5....6....2....0....2....3....3....6....5
..3....2....4....2....4....4....2....1....6....2....5....4....0....5....6....1
..4....2....3....5....4....4....1....0....6....2....1....0....3....3....7....5
..3....6....1....4....2....0....2....1....7....1....1....2....3....1....3....5
..3....0....3....4....5....4....5....1....3....3....1....2....6....3....6....6
..1....2....6....1....4....5....2....6....6....2....3....6....0....5....6....5
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Cf. A249707.

Formula

Empirical: a(n) = 4*a(n-1) -6*a(n-2) +4*a(n-3) +111*a(n-4) -308*a(n-5) +280*a(n-6) -84*a(n-7) -5194*a(n-8) +8288*a(n-9) -3066*a(n-10) +130820*a(n-12) -74128*a(n-13) -10560*a(n-14) -8848*a(n-15) -2004617*a(n-16) -633508*a(n-17) -130504*a(n-18) +130916*a(n-19) [phone]*a(n-20) [phone]*a(n-21) [phone]*a(n-22) +5552064*a(n-23) -132853024*a(n-24) -224564176*a(n-25) -190931472*a(n-26) -114274368*a(n-27) [phone]*a(n-28) [phone]*a(n-29) [phone]*a(n-30) [phone]*a(n-31) -1386528192*a(n-32) -4476415104*a(n-33) -5034923712*a(n-34) -3297853440*a(n-35) [phone]*a(n-36) [phone]*a(n-37) [phone]*a(n-38) [phone]*a(n-39) -1157068800*a(n-40) -7838208000*a(n-41) -7838208000*a(n-42) -2612736000*a(n-43).