A144855 Number of paths from (1,1) to (n,n) in an n X n grid using only the steps +(1,0), -(1,0), +(0,1) and -(0,1) which do not self-intersect and which avoid any point (p,q) satisfying "(p-1)*n + q is prime".

1, 0, 0, 0, 0, 0, 0, 254, 0, 0, 0, 0, 0

Offset

1,8

Links

Table of n, a(n) for n=1..13.

Example

One of the 254 prime avoiding paths for the n=8 case is 1,9,10,18,26,27,28,20,21,22,14,15,16,24,32,40,39,38,46,54,55,56,64

Crossrefs

Sequence in context: A243666 A243687 A263380 * A110827 A062664 A258696

Adjacent sequences: A144852 A144853 A144854 * A144856 A144857 A144858

Keyword

hard,more,nonn

Author

Joseph E. Cooper III (easonrevant(AT)gmail.com), Sep 22 2008

Status

approved