OFFSET
1,1
LINKS
R. H. Hardin, Table of n, a(n) for n = 1..210
R. H. Hardin, Empirical recurrence of order 78
Robert Israel, Maple-assisted proof of empirical recurrence
FORMULA
Empirical recurrence of order 78 (see link above).
Empirical recurrence verified (see link). - Robert Israel, Jul 30 2019
EXAMPLE
Some solutions for n=3
..1..2..1..0....3..4..3..2....3..4..3..4....2..0..2..0....1..1..2..1
..0..0..0..2....4..2..2..4....4..2..4..2....1..0..1..0....2..3..3..3
..1..2..1..0....4..3..4..3....2..3..2..3....0..2..2..2....2..4..5..4
..2..0..2..0....2..4..2..4....1..1..1..3....1..0..1..0....2..3..5..3
MAPLE
Rows:= [seq(seq(seq(seq([w, x, y, z], z=max(y-2, 0)..min(y+2, 5)), y=max(x-2, 0)..min(x+2, 5)), x=max(w-2, 0)..min(w+2, 5)), w=0..5)]:
nrows:= nops(Rows):
filter:= proc(x) local i, j; add(add((x[i]-x[j])^2, i=j+1..4), j=1..3)=11 end proc:
T:= Matrix(nrows, nrows, proc(i, j) local k; if andmap(filter, [seq([Rows[i][k], Rows[i][k+1], Rows[j][k], Rows[j][k+1]], k=1..3)]) then 1 else 0 fi end proc):
U[0]:= Vector(nrows, 1):
for j from 1 to 30 do U[j]:= T . U[j-1] od:
seq(add(U[n][i], i=1..nrows), n=1..30); # Robert Israel, Jul 30 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
R. H. Hardin, Dec 16 2013
STATUS
approved