A189430 Number of nX4 array permutations with each element not moving, or moving one space N, SW or SE.
1, 5, 29, 140, 841, 4653, 26589, 151081, 859264, 4891841, 27832869, 158410277, 901506585, 5130598532, 29198860965, 166174106629, 945717892865, 5382196223185, 30630747783536, 174323378425833, 992095956013449
Offset: 1
Keywords
Examples
Some solutions for 3X4 ..0..5..6..3....0..1..2..3....0..1..6..3....0..5..6..3....4..1..6..3 ..1..9.10..2....8..9..6..7....8..9.10..2....4..2..1..7....8..0.10..2 ..8..4..7.11....5..4.10.11....5..4..7.11....8..9.10.11....5..9..7.11
Links
- R. H. Hardin, Table of n, a(n) for n = 1..200
Formula
Empirical: a(n) = 4*a(n-1) +6*a(n-2) +15*a(n-3) +32*a(n-4) +31*a(n-5) -139*a(n-6) -38*a(n-7) -687*a(n-8) -1137*a(n-9) -2150*a(n-10) -2761*a(n-11) -2277*a(n-12) -6462*a(n-13) -713*a(n-14) -1533*a(n-15) +1533*a(n-17) +713*a(n-18) +6462*a(n-19) +2277*a(n-20) +2761*a(n-21) +2150*a(n-22) +1137*a(n-23) +687*a(n-24) +38*a(n-25) +139*a(n-26) -31*a(n-27) -32*a(n-28) -15*a(n-29) -6*a(n-30) -4*a(n-31) +a(n-32)
Comments