cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A305635 1 and odd numbers that are not perfect powers.

Original entry on oeis.org

1, 3, 5, 7, 11, 13, 15, 17, 19, 21, 23, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 79, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 111, 113, 115, 117, 119, 123, 127, 129, 131, 133, 135, 137
Offset: 1

Views

Author

Gus Wiseman, Jun 07 2018

Keywords

Crossrefs

Cf. A001597, A005117, A007916, A039956, A056911.
Cf. A305630, A305631, A305632, A305633, A305634.

Programs

  • Magma
    [1] cat  [n : n in [3..200 by 2] | not IsPower(n) ]; // Vincenzo Librandi, Jul 06 2018
  • Mathematica
    radQ[n_]:=Or[n==1,GCD@@FactorInteger[n][[All,2]]==1];
Select[Range[200],OddQ[#]&&radQ[#]&]
  • PARI
    isok(n) = (n==1) || ((n % 2) && !ispower(n)); \\ Michel Marcus, Jun 08 2018

A305634 Even numbers that are not perfect powers.

Original entry on oeis.org

2, 6, 10, 12, 14, 18, 20, 22, 24, 26, 28, 30, 34, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122, 124, 126, 130, 132, 134, 136, 138
Offset: 1

Views

Author

Gus Wiseman, Jun 07 2018

Keywords

Comments

Perfect powers are of the form m^k where m > 0 and k > 1 (A001597).

Examples

			10 is in the sequence since it is even and is not a power of an integer.  17 is not in the sequence since it is odd, and 36 is not in the sequence since it is a power of an integer (36 = 6^2).

Links

Crossrefs

Cf. A001597, A005117, A007916, A039956.
Cf. A305630, A305631, A305632, A305633, A305635.
Cf. A005843, A001597.

Programs

  • Maple
    N:= 1000:
S:={seq(i,i=2..N,2)} minus {seq(seq(e^m,m=2..floor(log[e](N))),e=2..floor(sqrt(N)),2)}:
sort(convert(S,list)); # Robert Israel, Jan 24 2019
  • Mathematica
    radQ[n_]:=Or[n==1,GCD@@FactorInteger[n][[All,2]]==1];
Select[Range[200],EvenQ[#]&&radQ[#]&]
  • PARI
    isok(n) = !(n % 2) && !ispower(n); \\ Michel Marcus, Jun 08 2018

Formula

A005843 \ A001597. - Eric Chen, Jun 14 2018
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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