A047720 Numbers that are the sum of 9 but no fewer nonzero fourth powers.

9, 24, 39, 54, 69, 89, 104, 119, 134, 144, 149, 169, 184, 199, 209, 214, 229, 249, 264, 279, 294, 309, 329, 344, 359, 374, 384, 389, 404, 409, 424, 439, 449, 454, 469, 484, 489, 504, 519, 534, 549, 564, 569, 579, 584, 599, 614, 624, 633, 649, 664, 679, 694

Offset: 1

Author

Arlin Anderson (starship1(AT)gmail.com)

Keywords

• nonn

Links

• David A. Corneth, Table of n, a(n) for n = 1..16848 (first terms <= 200000)

Crossrefs

Cf. A000583, A002377, A003343.

Programs

PARI

upto(n)={my(e=9); my(s=sum(k=1, sqrtint(sqrtint(n)), x^(k^4)) + O(x*x^n)); my(p=s^e, q=(1 + s)^(e-1)); select(k->polcoeff(p,k) && !polcoeff(q,k), [1..n])} \\ Andrew Howroyd, Jul 06 2018