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A323141 Number of self-trapped uncrossed king's paths on an infinite board after n steps, reduced for symmetry. 5
0, 0, 0, 0, 2, 19, 150, 1043, 6843, 43192, 266529, 1619983, 9746883, 58220994, 345919915 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..15.

EXAMPLE

a(5) = 2: There are 2 walks where the king is blocked after 5 steps, because for the diagonal moves it would have to cross its previous path.

.

  o       2       o       o       3        o

        /   \                   /   \

      /       \               /        \

    /           \           /            \

  3       5       1       4 - - - 5        2

  |     /       /                        /

  |   /       /                        /

  | /       /                        /

  4       S       o       S - - -  1       o

CROSSREFS

Cf. A003192, A077482, A272773, A323140.

Sequence in context: A220792 A220957 A280546 * A319962 A161608 A037748

Adjacent sequences:  A323138 A323139 A323140 * A323142 A323143 A323144

KEYWORD

nonn,more,hard

AUTHOR

Hugo Pfoertner, Jan 05 2019

STATUS

approved

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Last modified January 22 00:08 EST 2022. Contains 350481 sequences. (Running on oeis4.)