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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A135572 A number n is included if the largest prime-power dividing n is a square. 0
1, 4, 9, 12, 16, 18, 25, 36, 45, 48, 49, 50, 63, 64, 72, 75, 80, 81, 90, 98, 100, 112, 121, 126, 144, 147, 150, 162, 169, 175, 176, 180, 192, 196, 200, 208, 225, 240, 242, 245, 252, 256, 275, 289, 294, 300, 315, 320, 324, 325, 336, 338, 350, 360, 361, 363, 392 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

1 is included in the sequence because 1 is sometimes considered to be a prime-power.

LINKS

Table of n, a(n) for n=1..57.

EXAMPLE

The largest prime-power dividing 12 is 4. Since 4 is a square, then 12 is included in the sequence. On the other hand, the largest prime-power dividing 24 is 8. Since 8 is not a square, then 24 is not in the sequence.

MAPLE

omega := proc(n) nops( numtheory[factorset](n)) ; end: isA000961 := proc(n) RETURN(n = 1 or omega(n) =1) ; end: A034699 := proc(n) local dvs, d ; dvs := sort(convert(numtheory[divisors](n), list), `>`) ; for d in dvs do if isA000961(d) then RETURN(d) ; fi ; od: end: isA135572 := proc(n) issqr(A034699(n)) ; end: for n from 1 to 800 do if isA135572(n) then printf("%d, ", n) ; fi ; end: # R. J. Mathar, May 24 2008

MATHEMATICA

Join[{1}, Select[Range[400], IntegerQ[Sqrt[Max[Select[Divisors[#], PrimePowerQ]]]]&]] (* Harvey P. Dale, Aug 03 2017 *)

CROSSREFS

Cf. A034699.

Sequence in context: A072587 A240112 A162645 * A337103 A312855 A312856

Adjacent sequences:  A135569 A135570 A135571 * A135573 A135574 A135575

KEYWORD

nonn

AUTHOR

Leroy Quet, May 10 2008

EXTENSIONS

More terms from R. J. Mathar, May 24 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 November 27 04:07 EST 2020. Contains 338677 sequences. (Running on oeis4.)