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A257855 a(n) = 2*n^5 - floor(2^(1/5)*n)^5. 2
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 (list; graph; refs; listen; history; text; internal format)
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: A250363 A017674 A184979 * A055014 A000584 A050752

Adjacent sequences:  A257852 A257853 A257854 * A257856 A257857 A257858

KEYWORD

nonn,easy

AUTHOR

M. F. Hasler, May 28 2015

STATUS

approved

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Last modified August 1 00:13 EDT 2021. Contains 346377 sequences. (Running on oeis4.)