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A053589 Greatest primorial number (A002110) which divides n. 9
1, 2, 1, 2, 1, 6, 1, 2, 1, 2, 1, 6, 1, 2, 1, 2, 1, 6, 1, 2, 1, 2, 1, 6, 1, 2, 1, 2, 1, 30, 1, 2, 1, 2, 1, 6, 1, 2, 1, 2, 1, 6, 1, 2, 1, 2, 1, 6, 1, 2, 1, 2, 1, 6, 1, 2, 1, 2, 1, 30, 1, 2, 1, 2, 1, 6, 1, 2, 1, 2, 1, 6, 1, 2, 1, 2, 1, 6, 1, 2, 1, 2, 1, 6, 1, 2, 1, 2, 1, 30, 1, 2, 1, 2, 1, 6, 1, 2, 1, 2, 1, 6 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..2309

Index entries for sequences related to primorial numbers

FORMULA

From Antti Karttunen, Aug 30 2016: (Start)

a(n) = A002110(A276084(n)).

a(n) = n/A111701(n).

A276157(n) = A260188(n)/a(n).

(End)

EXAMPLE

a(30) = 30 because 30=2*3*5, a(15) = 1 because 15=3*5.

MAPLE

N:= 1000: # to get a(1)..a(N)

P:= 1: p:= 1:

A:= Vector(N, 1):

do

  p:= nextprime(p);

  P:= P*p;

  if P > N then break fi;

  A[[seq(i, i=P..N, P)]]:= P;

od:

convert(A, list); # Robert Israel, Aug 30 2016

MATHEMATICA

Table[k = 1; While[Divisible[n, Times @@ Prime@ Range@ k], k++]; Times @@ Prime@ Range[k - 1], {n, 120}] (* Michael De Vlieger, Aug 30 2016 *)

PROG

(Scheme) (define (A053589 n) (A002110 (A276084 n))) ;; Antti Karttunen, Aug 30 2016

(PARI) a(n)=my(f=factor(n), r = 1, k = 1, p); while(k<=matsize(f)[1], p=prime(k); if(f[k, 1]!=p, return(r)); r*=p; k++) ; r

a(n) = my(r = 1, p = 2); while(n/p==n\p, r*=p; p=nextprime(p+1)); r

\\ list of all terms upto n#.

lista(n) = my(l = List([1]), k, s=1); forprime(i=2, n, for(j=1, i-1, for(k=1, s, listput(l, l[k]))); l[#l]*=i; s=#l); l \\ David A. Corneth, Aug 30 2016

(PARI) a(n)=my(s=1); forprime(p=2, , if(n%p, return(s), s *= p)) \\ Charles R Greathouse IV, Sep 07 2016

CROSSREFS

Cf. A002110, A276084, A053669, A111701, A276151, A276152, A276157, A260188, A276086, A276150.

Sequence in context: A086545 A126083 A071416 * A055770 A225821 A113766

Adjacent sequences:  A053586 A053587 A053588 * A053590 A053591 A053592

KEYWORD

nonn,easy

AUTHOR

Frederick Magata (frederick.magata(AT)uni-muenster.de), Jan 19 2000

EXTENSIONS

More terms from Larry Reeves (larryr(AT)acm.org), Oct 02 2000

STATUS

approved

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Last modified May 19 13:11 EDT 2019. Contains 323393 sequences. (Running on oeis4.)