OFFSET
1,4
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..250
EXAMPLE
a(4) = 6: [1,1,1,1], [1,1,2], [1,2,1], [1,3], [2,1,1], [3,1].
MAPLE
b:= proc(n, t, g, k) option remember;
`if`(n=0, `if`(igcd(g, t)=1 and igcd(k, t)=1 and igcd(g, k)=1, 1, 0),
add(b(n-i, t+1, max(i, g), min(i, k)), i=1..n))
end:
a:= n-> b(n, 0, 0, infinity):
seq(a(n), n=1..40);
MATHEMATICA
b[n_, t_, g_, k_] := b[n, t, g, k] = If[n == 0, If[GCD[g, t] == 1 && GCD[k, t] == 1 && GCD[g, k] == 1, 1, 0], Sum[b[n-i, t+1, Max[i, g], Min[i, k]], {i, 1, n}]]; a[n_] := b[n, 0, 0, Infinity]; Table[a[n], {n, 1, 40}] (* Jean-François Alcover, Nov 05 2014, after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Nov 11 2011
STATUS
approved