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A220612 Number of ways to reciprocally link elements of an nX6 array either to themselves or to exactly two horizontal and vertical neighbors, without consecutive collinear links 1
1, 13, 43, 281, 1277, 7041, 34981, 183920, 937663, 4861869, 24977087, 128971605, 664092737, 3424806465, 17647051243, 90973240309, 468858278192, 2416753993341, 12456282450653, 64204249763017, 330924094972255, 1705685462529549 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Column 6 of A220614
LINKS
FORMULA
Empirical: a(n) = 3*a(n-1) +23*a(n-2) -40*a(n-3) -160*a(n-4) +190*a(n-5) +441*a(n-6) -369*a(n-7) -513*a(n-8) +278*a(n-9) +240*a(n-10) -64*a(n-11) -39*a(n-12) +3*a(n-13) +a(n-14)
EXAMPLE
Some solutions for n=3 0=self 2=n 4=w 6=e 8=s (reciprocal directions total 10)
.68.48.00.00.00.00...00.00.00.68.48.00...68.48.68.48.00.00...68.48.68.48.68.48
.26.24.00.00.68.48...00.00.00.26.24.00...26.24.26.24.68.48...26.24.26.24.26.24
.00.00.00.00.26.24...00.00.00.00.00.00...00.00.00.00.26.24...00.00.00.00.00.00
CROSSREFS
Sequence in context: A242548 A104115 A063650 * A144236 A082689 A228505
KEYWORD
nonn
AUTHOR
R. H. Hardin Dec 17 2012
STATUS
approved

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Last modified April 25 03:15 EDT 2024. Contains 371964 sequences. (Running on oeis4.)