A140823 Integers that are not perfect fourth powers.

2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74

Offset

1,1

Comments

First differs from A046100 at {32, 48, 64, 80, 96, 112, 144, 160, 162, ...}.

Links

Table of n, a(n) for n=1..72.

A. J. dos Reis and D. M. Silberger, Generating nonpowers by formula, Math. Mag., 63 (1990), 53-55.

Formula

{a(n) in A000027 and a(n) not in A000583}.

Mathematica

Module[{nn=100, fp}, fp=Floor[Surd[nn, 4]]; Complement[Range[nn], Range[ fp]^4]] (* Harvey P. Dale, Dec 09 2013 *)

Prog

(Python)
from sympy import integer_nthroot
def A140823(n): return n+(k:=integer_nthroot(n, 4)[0])+int(n>=(k+1)**4-k) # Chai Wah Wu, Jun 17 2024

Crossrefs

Cf. A000037, A000583, A007412, A046100.

Sequence in context: A032951 A288139 A194897 * A209061 A115063 A369939

Adjacent sequences: A140820 A140821 A140822 * A140824 A140825 A140826

Keyword

easy,nonn

Author

Jonathan Vos Post, Jul 17 2008

Status

approved