A220615 Number of ways to reciprocally link elements of an n X n array either to themselves or to exactly one horizontal, diagonal and antidiagonal neighbor.
1, 7, 125, 17084, 8608738, 24177895648, 304265433695569, 19162399246164949616, 5720357296116644040788320, 8308397301115322562870135405329, 57991968922890673398646650823295660128
Offset: 1
Keywords
Examples
Some solutions for n=3 0=self 1=nw 3=ne 4=w 6=e 7=sw 9=se (reciprocal directions total 10) ..0..9..7....0..6..4....0..0..0....6..4..0....0..0..0....9..0..0....0..9..0 ..9..3..1....0..7..7....0..0..0....0..6..4....0..9..0....0..1..0....0..7..1 ..0..1..0....3..3..0....0..0..0....0..0..0....6..4..1....0..6..4....3..0..0
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