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A164347 The n-th term is the minimum number x such that x/Totient(x) >= n 1
2, 2, 6, 30, 210, 30030, 223092870, 13082761331670030, 3217644767340672907899084554130 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

These numbers are all primorials. Primorials necessarily must be the minimum terms in this sequence (given the nature of Euler's Totient function).

Essentially the same as A091456. - R. J. Mathar, Aug 17 2009

LINKS

Table of n, a(n) for n=1..9.

Wikipedia, Euler's totient function

EXAMPLE

2 => 2/ Totient(2) = 2 (so it is both the first and 2nd entry of the sequence) 210 => 210 / Totient(210) = 210/48 >= 4

PROG

(PARI) mm=3; n=2; m=1; forprime(x=3, 1000, n*=x; m*= (x-1); if (n\m >= mm, mm+=1; print(n))); /* Note: this will generate all terms of this sequence from the 3rd onward. The terms are easy to generate but grow very rapidly */

CROSSREFS

Each number n in this sequence is of the form: primorial(x). A164348, the related sequence, contains the x's.

Sequence in context: A067644 A184312 A097801 * A052584 A094303 A117394

Adjacent sequences:  A164344 A164345 A164346 * A164348 A164349 A164350

KEYWORD

easy,nonn

AUTHOR

Fred Schneider, Aug 13 2009

STATUS

approved

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Last modified May 9 04:40 EDT 2021. Contains 343687 sequences. (Running on oeis4.)