OFFSET
0,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..500
EXAMPLE
MAPLE
s:= subsop:
b:= proc(n, l) option remember; local k, t; t:= min(l[]);
if n=0 then 1 elif t>0 then b(n-t, map(h->h-t, l))
else for k while l[k]>0 do od; add(`if`(n>=j,
b(n, s(k=j, l)), 0), j=2..3)+ `if`(k<=4 and l[k+2]=0,
b(n, s(k=1, k+2=1, l))+ `if`(k<=2 and l[k+4]=0,
b(n, s(k=1, k+2=1, k+4=1, l)), 0), 0)+ `if`(
irem(k, 2)>0 and l[k+1]=0, b(n, s(k=1, k+1=1, l)), 0)
fi
end:
a:=n-> b(n, [0$6]):
seq(a(n), n=0..25);
MATHEMATICA
b[n_, l_] := b[n, l] = Module[{k, t}, t = Min[l]; If [n == 0, 1, If[t > 0, b[n-t, l-t], k = 1; While[l[[k]] > 0 , k++]; Sum[If[n >= j, b[n, ReplacePart[l, k -> j]], 0], {j, 2, 3}] + If[k <= 4 && l[[k+2]] == 0, b[n, ReplacePart[l, {k -> 1, k+2 -> 1}]] + If[k <= 2 && l[[k+4]] == 0, b[n, ReplacePart[l, {k -> 1, k+2 -> 1, k+4 -> 1}]], 0], 0] + If[Mod[k, 2] > 0 && l[[k+1]] == 0, b[n, ReplacePart[l, {k -> 1, k+1 -> 1}]], 0] ] ] ]; a[n_] := b[n, Array[0&, 6]]; Table[a[n], {n, 0, 25}] (* Jean-François Alcover, Dec 16 2013, translated from Maple *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Dec 07 2013
STATUS
approved