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A140823
Integers that are not perfect fourth powers.
3
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
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
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Jul 17 2008
STATUS
approved