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!)
A271613 Number of ways to reciprocally link elements of an n X n X n triangular array with themselves or a neighbor, with no more than 4 elements linked to themselves. 0
1, 4, 26, 307, 2571, 42702, 3243689, 132728354, 1491326272, 101843558868, 74672717363118, 12952235029243936, 334070494079203752, 109915013016304822208, 695394278635888843298780, 579704015638436450676621584, 44655320458467210977882177104, 75051772861714827753881814035744 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Column 4 of A271617.

LINKS

Table of n, a(n) for n=1..18.

EXAMPLE

Some solutions for n=4

.....5........0........0........0........0........0........0........5

....2.0......4.3......0.0......6.0......0.0......4.3......6.6......2.6

...5.4.3....5.0.6....5.4.3....5.1.6....6.4.3....4.3.5....5.1.1....5.0.1

..2.4.3.0..2.4.3.1..2.0.4.3..2.4.3.1..0.1.4.3..4.3.2.0..2.4.3.0..2.4.3.0

Element moves: 0=itself 1=nw 2=ne 3=w 4=e 5=sw 6=se, reciprocals total 7

CROSSREFS

Cf. A271617.

Sequence in context: A156306 A054592 A102202 * A271614 A136503 A114125

Adjacent sequences:  A271610 A271611 A271612 * A271614 A271615 A271616

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 10 2016

EXTENSIONS

a(15)-a(18) from Alois P. Heinz, Jun 15 2017

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 June 25 10:28 EDT 2021. Contains 345453 sequences. (Running on oeis4.)