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!)
A220734 Number of ways to reciprocally link elements of an nX4 array either to themselves or to exactly two horizontal, diagonal and antidiagonal neighbors, without consecutive collinear links 1
1, 13, 103, 712, 5760, 45421, 355883, 2807273, 22112517, 174154372, 1371967416, 10807412577, 85133340257, 670628304993, 5282781003159, 41614380864876, 327811678257588, 2582291933091677, 20341654064411427, 160238619700892677 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 4 of A220738

LINKS

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

FORMULA

Empirical: a(n) = 9*a(n-1) -4*a(n-2) -23*a(n-3) -153*a(n-4) +204*a(n-5) +564*a(n-6) -700*a(n-7) +95*a(n-8) +2061*a(n-9) -3000*a(n-10) -4459*a(n-11) +2151*a(n-12) +5800*a(n-13) +320*a(n-14) -1276*a(n-15) -925*a(n-16) +233*a(n-17) +48*a(n-18) +13*a(n-19) -a(n-20)

EXAMPLE

Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10)

.00.69.49.00...00.69.49.00...00.69.47.00...00.67.49.00...69.47.00.00

.00.00.17.17...69.47.16.14...00.39.16.47...36.47.67.14...39.16.47.00

.00.36.34.00...36.14.00.00...00.00.13.00...36.34.00.00...00.13.00.00

CROSSREFS

Sequence in context: A119594 A066034 A228213 * A268991 A216179 A240804

Adjacent sequences:  A220731 A220732 A220733 * A220735 A220736 A220737

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 September 16 18:26 EDT 2021. Contains 347473 sequences. (Running on oeis4.)