login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A007412 The noncubes: n + [ (n + [ n^{1/3} ])^{1/3} ].
(Formerly M0493)
14
2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Seems to be numbers n for which order of torsion subgroup t of the elliptic curve y^2=x^3-n is t=1. [Artur Jasinski, Jun 30 2010]

A010057(a(n)) = 0. [Reinhard Zumkeller, Oct 22 2011]

REFERENCES

J. Roberts, Lure of the Integers, Math. Assoc. America, 1992, p. 27911

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

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

J. Gebel, Integer points on Mordell curves [Cached copy, after the original web site tnt.math.se.tmu.ac.jp was shut down in 2017]

Henry W. Gould, Letters to N. J. A. Sloane, Oct 1973 and Jan 1974.

R. D. Nelson, Sequences which omit powers, The Mathematical Gazette, Number 461, 1988, pages 208-211.

FORMULA

a(n) = n + A048766(n + A048766(n)). [Reinhard Zumkeller, Oct 22 2011]

MATHEMATICA

With[{upto=58}, Complement[Range[upto], Range[Ceiling[Power[upto, (3)^-1]]]^3]] (* Harvey P. Dale, Nov 09 2011 *)

A007412Q = ! IntegerQ[#~Surd~3] &; Select[Range[57], A007412Q] (* JungHwan Min, Mar 27 2017 *)

PROG

(Haskell)

a007412 n = n + a048766 (n + a048766 n)  -- Reinhard Zumkeller, Oct 22 2011

(PARI) lista(nn) = for (n=1, nn, if (! ispower(n, 3), print1(n, ", "))); \\ Michel Marcus, May 24 2015

CROSSREFS

Cf. A000578 (complement), A000037 (nonsquares).

Sequence in context: A102352 A248182 A219227 * A270420 A220218 A096432

Adjacent sequences:  A007409 A007410 A007411 * A007413 A007414 A007415

KEYWORD

nonn,easy,nice,changed

AUTHOR

N. J. A. Sloane.

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified June 24 11:32 EDT 2017. Contains 288697 sequences.