A004893 Numbers that are the sum of at most 9 positive 9th powers.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 512, 513, 514, 515, 516, 517, 518, 519, 520, 1024, 1025, 1026, 1027, 1028, 1029, 1030, 1031, 1536, 1537, 1538, 1539, 1540, 1541, 1542, 2048, 2049, 2050, 2051, 2052, 2053, 2560, 2561, 2562, 2563, 2564, 3072, 3073, 3074, 3075, 3584

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^9<=n and b(n-i^9, 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, 9), 9) do od; k
    end:
seq(a(n), n=1..60);  # Alois P. Heinz, Sep 16 2016

Mathematica

b[n_, k_, i_, t_] := b[n, k, i, t] = n == 0 || i > 0 && t > 0 && (b[n, k, i - 1, t] || i^k <= n && b[n - i^k, k, i, t - 1]);
A[n_, k_] := A[n, k] = Module[{m}, For[m = 1 + If[n == 1, -1, A[n - 1, k]], !b[m, k, m^(1/k) // Floor, k], m++]; m];
a[n_] := A[n, 9];
Table[a[n], {n, 1, 60}] (* Jean-François Alcover, May 20 2022, after Alois P. Heinz in A336820 *)

Crossrefs

Column k=9 of A336820.

Sequence in context: A307887 A362843 A344822 * A069282 A069747 A308126

Adjacent sequences: A004890 A004891 A004892 * A004894 A004895 A004896

Keyword

nonn

Author

N. J. A. Sloane

Extensions

More terms from Alois P. Heinz, Sep 16 2016

Status

approved