login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A137257 A number n is included if there is at least one (nonzero) exponent in the prime factorization of n that is not coprime to n. 1
4, 12, 16, 18, 20, 24, 27, 28, 36, 44, 48, 50, 52, 54, 60, 64, 68, 72, 76, 80, 84, 90, 92, 98, 100, 108, 112, 116, 120, 124, 126, 132, 135, 140, 144, 148, 150, 156, 160, 162, 164, 168, 172, 176, 180, 188, 189, 192, 196, 198, 200, 204, 208, 212, 216, 220, 228, 234 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..58.

EXAMPLE

48 = 2^4 * 3^1; so the exponents in the prime-factorization of 48 are 4 and 1. 48 is not coprime to 4; therefore 48 is included in this sequence.

MATHEMATICA

Select[Range[3000], GCD[ #, Product[FactorInteger[ # ][[i, 2]], {i, 1, Length[FactorInteger[ # ]]}]] > 1 &] (* Stefan Steinerberger, Mar 16 2008 *)

CROSSREFS

Sequence in context: A163838 A228091 A157849 * A144976 A119622 A280892

Adjacent sequences:  A137254 A137255 A137256 * A137258 A137259 A137260

KEYWORD

nonn

AUTHOR

Leroy Quet, Mar 11 2008

EXTENSIONS

More terms from Stefan Steinerberger, Mar 16 2008

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 10 16:56 EDT 2020. Contains 336381 sequences. (Running on oeis4.)