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A329872 Nontotients (A005277) that are the product of two totients (A002202). 1
484, 968, 1100, 2116, 3364, 4232, 6084, 6724, 6728, 8464, 10404, 11132, 11236, 13448, 16928, 19044, 22472, 26896, 27556, 29584, 31684, 36100, 44944, 51076, 53792, 55112, 56644, 59168, 63368, 65824, 67416, 68644, 72200, 79524, 80344, 89888, 96100, 99856, 102152, 107584 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

We can have a list of nontotients and their factorizations into two totients. A totient m is in A301587 if and only if m never occurs in this list as a divisor of the nontotients. Using the list, many totients (10, 22, 44, 46, ...) are ruled out of A301587. But generally it's hard to prove that a number is in A301587.

LINKS

Jianing Song, Table of n, a(n) for n = 1..7280 (All terms <= 10^8)

Jianing Song, Nontotients, and their factorizations into two totients

EXAMPLE

484 is here, because 484 = 22*22, and 22 is a totient while 484 isn't. Similarly, if p == 3 (mod 4) is a prime such that (p-1)^2+1 is composite, then (p-1)^2 is here.

PROG

(PARI) isA329872(n) = if(!istotient(n), my(v=divisors(n)); for(i=1, #v, if(istotient(v[i])&&istotient(n/v[i]), return(1))); 0)

CROSSREFS

Cf. A002202, A005277, A301587.

Sequence in context: A156646 A177434 A202444 * A199330 A281398 A014803

Adjacent sequences:  A329869 A329870 A329871 * A329873 A329874 A329875

KEYWORD

nonn

AUTHOR

Jianing Song, Nov 23 2019

STATUS

approved

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Last modified February 22 18:24 EST 2020. Contains 332148 sequences. (Running on oeis4.)