login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A220707 Number of ways to reciprocally link elements of an nX7 array either to themselves or to exactly two horizontal and antidiagonal neighbors, without consecutive collinear links 1
1, 13, 48, 298, 1520, 8338, 44976, 244029, 1322551, 7171769, 38885648, 210854845, 1143330649, 6199601829, 33616711696, 182283373322, 988413912488, 5359579124490, 29061800830768, 157584813722329, 854488462716575 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 7 of A220708

LINKS

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

FORMULA

Empirical: a(n) = 5*a(n-1) +6*a(n-2) -17*a(n-3) -19*a(n-4) +10*a(n-5) +16*a(n-6) -46*a(n-7) +7*a(n-8) +15*a(n-9) -14*a(n-10) +21*a(n-11) +3*a(n-12) +10*a(n-13) +8*a(n-14) +2*a(n-15) +5*a(n-16) +a(n-17) +2*a(n-18) -a(n-19) -a(n-20)

EXAMPLE

Some solutions for n=3 0=self 3=ne 4=w 6=e 7=sw (reciprocal directions total 10)

.00.00.00.00.00.00.00...00.00.00.00.00.00.00...00.67.47.00.00.00.00

.00.00.67.47.00.00.00...00.00.67.47.67.47.00...36.34.00.00.00.67.47

.00.36.34.00.00.00.00...00.36.34.36.34.00.00...00.00.00.00.36.34.00

CROSSREFS

Sequence in context: A027980 A200254 A288746 * A189349 A013200 A156694

Adjacent sequences:  A220704 A220705 A220706 * A220708 A220709 A220710

KEYWORD

nonn

AUTHOR

R. H. Hardin Dec 18 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 14 22:39 EDT 2021. Contains 342962 sequences. (Running on oeis4.)