A255659 Number of length n+7 0..3 arrays with at most two downsteps in every 7 consecutive neighbor pairs.

28722, 83752, 265430, 864924, 2816673, 9169016, 29577432, 92530816, 286454024, 900260308, 2873064972, 9187712072, 29298245258, 93413733472, 297026093532, 940176646792, 2973476370798, 9435365703664, 30019424281120, 95485615550472

Offset: 1

Author

R. H. Hardin, Mar 01 2015

Keywords

• nonn

Comments

Column 7 of A255660

Examples

			Some solutions for n=2
..0....0....2....0....3....3....0....0....2....3....1....0....2....2....1....0
..0....1....3....0....3....0....1....3....2....1....2....0....0....0....3....2
..0....2....0....2....3....2....0....1....3....2....2....3....2....0....3....3
..3....1....2....2....0....2....0....1....3....3....2....0....2....2....2....3
..1....1....3....2....0....1....0....0....3....1....2....2....3....1....2....3
..1....3....0....0....1....1....0....3....0....1....2....2....3....2....1....1
..3....3....2....2....3....2....0....3....2....2....0....0....3....3....2....1
..3....0....3....2....0....3....1....3....1....3....3....0....1....3....2....0
..2....3....3....3....0....2....0....3....1....3....1....0....0....1....3....3
		

Links

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

Crossrefs

Cf. A255660

Formula

Empirical: a(n) = 4*a(n-1) -6*a(n-2) +4*a(n-3) +30*a(n-4) -72*a(n-5) +58*a(n-6) +872*a(n-7) -2121*a(n-8) +1748*a(n-9) -492*a(n-10) -13640*a(n-11) +26816*a(n-12) -13536*a(n-13) -232948*a(n-14) +493540*a(n-15) -280547*a(n-16) -33840*a(n-17) +1271000*a(n-18) -2599020*a(n-19) +2012477*a(n-20) [phone]*a(n-21) -38149820*a(n-22) [phone]*a(n-23) -9358211*a(n-24) -17204016*a(n-25) [phone]*a(n-26) -6417756*a(n-27) -25522136*a(n-28) [phone]*a(n-29) -10417774*a(n-30) -104220*a(n-31) [phone]*a(n-32) -9721216*a(n-33) -6417184*a(n-34) [phone]*a(n-35) -11470236*a(n-36) -3073784*a(n-37) +2563240*a(n-38) -4701200*a(n-39) +5023520*a(n-40) -1940960*a(n-41) -2778800*a(n-42) +3580160*a(n-43) -1109600*a(n-44) +16000*a(n-45) +88000*a(n-46) +22400*a(n-47) +10000*a(n-48)