OFFSET
1,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..10000
MAPLE
b:= proc(n, i, t) option remember; n=0 or i>0 and t>0
and (b(n, i-1, t) or i^5<=n and b(n-i^5, i, t-1))
end:
a:= proc(n) option remember; local k;
for k from 1+ `if`(n=1, -1, a(n-1))
while not b(k, iroot(k, 5), 4) do od; k
end:
seq(a(n), n=1..50); # Alois P. Heinz, Sep 16 2016
MATHEMATICA
b[n_, i_, t_] := b[n, i, t] = n==0 || i>0 && t>0 && (b[n, i-1, t] || i^5 <= n && b[n - i^5, i, t-1]);
a[n_] := a[n] = Module[{k}, For[k = 1+If[n==1, -1, a[n-1]], !b[k, Floor[ k^(1/5)], 4], k++]; k];
Array[a, 50] (* Jean-François Alcover, Nov 16 2020, after Alois P. Heinz *)
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved