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

1,1

Comments

Column 7 of A249707.

Links

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

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) +20088708*a(n-20) +21173952*a(n-21) +13092164*a(n-22) +5552064*a(n-23) -132853024*a(n-24) -224564176*a(n-25) -190931472*a(n-26) -114274368*a(n-27) +557555040*a(n-28) +1305213120*a(n-29) +1329331968*a(n-30) +881028864*a(n-31) -1386528192*a(n-32) -4476415104*a(n-33) -5034923712*a(n-34) -3297853440*a(n-35) +1793560320*a(n-36) +8714615040*a(n-37) +10059033600*a(n-38) +5654707200*a(n-39) -1157068800*a(n-40) -7838208000*a(n-41) -7838208000*a(n-42) -2612736000*a(n-43).

Example

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

Crossrefs

Cf. A249707.

Sequence in context: A115496 A252390 A218158 * A098237 A068856 A235949

Adjacent sequences: A249703 A249704 A249705 * A249707 A249708 A249709

Keyword

nonn

Author

R. H. Hardin, Nov 04 2014

Status

approved