login
A004881
Numbers that are the sum of at most 8 nonzero 8th powers.
2
0, 1, 2, 3, 4, 5, 6, 7, 8, 256, 257, 258, 259, 260, 261, 262, 263, 512, 513, 514, 515, 516, 517, 518, 768, 769, 770, 771, 772, 773, 1024, 1025, 1026, 1027, 1028, 1280, 1281, 1282, 1283, 1536, 1537, 1538, 1792, 1793, 2048, 6561, 6562, 6563, 6564, 6565, 6566
OFFSET
1,3
LINKS
MAPLE
b:= proc(n, i, t) option remember; n=0 or i>0 and t>0
and (b(n, i-1, t) or i^8<=n and b(n-i^8, 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, 8), 8) do od; k
end:
seq(a(n), n=1..60); # 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^8 <= n && b[n - i^8, i, t - 1]);
a[n_] := a[n] = (For[k = 1 + If[n == 1, -1, a[n - 1]], !b[k, k^(1/8) // Floor, 8], k++]; k);
Array[a, 60] (* Jean-François Alcover, Apr 06 2017, after Alois P. Heinz *)
CROSSREFS
Column k=8 of A336820.
Sequence in context: A037443 A073790 A029965 * A004892 A365822 A004903
KEYWORD
nonn
EXTENSIONS
More terms from Alois P. Heinz, Sep 16 2016
STATUS
approved