A257855 a(n) = 2*n^5 - floor(2^(1/5)*n)^5.

0, 1, 32, 243, 1024, 3125, 7776, 846, 6487, 18098, 38949, 73270, 126371, 204762, 27072, 98893, 207584, 363615, 579136, 868097, 1246368, 205578, 541639, 991310, 1576341, 2320882, 3251603, 68663, 866304, 1886905, 3164576, 4736427, 6642688, 8926829, 646649, 2643750

Offset

0,3

Comments

Is there a simple expression for a nontrivial lower bound for a(n)?

Links

Table of n, a(n) for n=0..35.

Example

a(6) = 2*6^5 - floor(2^(1/5)*6)^5 = 2*7776 - 6^5 = 7776.
a(7) = 2*7^5 - floor(2^(1/5)*7)^5 = 2*16807 - 8^5 = 846.

Mathematica

Table[2 n^5 - Floor[2^(1/5) n]^5, {n, 0, 60}] (* Vincenzo Librandi, May 29 2015 *)

Prog

(PARI) f(n, e=5, b=2)=n^e*b-floor(sqrtn(b, e)*n)^e
(Magma) [2*n^5 - Floor(2^(1/5)*n)^5: n in [0..50]]; // Vincenzo Librandi, May 29 2015

Crossrefs

Cf. A087056 (analog for squares), A257853, A257854 (3rd & 4th power).

Sequence in context: A346637 A017674 A184979 * A055014 A000584 A352051

Adjacent sequences: A257852 A257853 A257854 * A257856 A257857 A257858

Keyword

nonn,easy

Author

M. F. Hasler, May 28 2015

Status

approved