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A291548 Numbers n such that uphi(n) does not divide uphi(n!). 0
4, 8, 24, 27, 32, 96, 2187, 8192, 24576, 131072, 155648, 393216, 524288, 655360, 917504, 1572864, 1594323, 3188646, 6377292, 48828125, 97656250 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Terms are 2^2, 2^3, 3*2^3, 3^3, 2^5, 3*2^5, 3^7, 2^13, 3*2^13, ...

LINKS

Table of n, a(n) for n=1..21.

EXAMPLE

4 is a term because uphi(4) = 3 does not divide uphi(4!) = 14.

PROG

(PARI) valp(n, p)=my(s); while(n\=p, s+=n); s

uphi(n, f=factor(n))=prod(i=1, #f~, f[i, 1]^f[i, 2]-1)

is(n)=my(m=uphi(n), t); forprime(p=2, n, t=gcd(lift(Mod(p, m)^valp(n, p)-1), m); if(t>1, m/=t; if(m==1, return(0)))); m>1 \\ Charles R Greathouse IV, Aug 27 2017

CROSSREFS

Cf. A047994.

Sequence in context: A083504 A277291 A254731 * A212019 A075708 A066617

Adjacent sequences:  A291545 A291546 A291547 * A291549 A291550 A291551

KEYWORD

nonn,more

AUTHOR

Altug Alkan, Aug 26 2017

EXTENSIONS

a(10)-a(19) from Charles R Greathouse IV, Aug 27 2017

a(20) from Charles R Greathouse IV, Sep 06 2017

a(21) from Charles R Greathouse IV, Oct 12 2017

STATUS

approved

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Last modified October 19 13:01 EDT 2019. Contains 328222 sequences. (Running on oeis4.)