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A220559 Number of ways to reciprocally link elements of an n X 5 array either to themselves or to exactly one horizontal or antidiagonal neighbor. 1
8, 149, 2604, 45966, 810778, 14298089, 252139015, 4446314533, 78407942556, 1382674335890, 24382584703194, 429971411669361, 7582273047532603, 133708574584054949, 2357865880743076540, 41579468847568886038 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Column 5 of A220562.
LINKS
FORMULA
Empirical: a(n) = 21*a(n-1) - 62*a(n-2) + 47*a(n-3) - 5*a(n-4) for n>5.
Empirical g.f.: x*(8 - 19*x - 29*x^2 + 144*x^3 - 23*x^4) / ((1 - x)*(1 - 20*x + 42*x^2 - 5*x^3)). - Colin Barker, Jul 31 2018
EXAMPLE
Some solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10):
..0..0..0..6..4....0..0..0..6..4....0..0..0..6..4....0..0..6..4..0
..6..4..0..6..4....0..6..4..0..0....0..6..4..7..0....0..7..7..7..0
..0..6..4..0..0....0..6..4..0..0....0..0..3..0..0....3..3..3..0..0
CROSSREFS
Cf. A220562.
Sequence in context: A244028 A075351 A302063 * A264642 A300872 A217502
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 16 2012
STATUS
approved

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Last modified March 1 09:59 EST 2024. Contains 370432 sequences. (Running on oeis4.)