A361686 a(n) is the least totient divisor of A329872(n), where A329872 are nontotients (A005277) that are the product of two totients (A002202).

22, 22, 10, 46, 58, 46, 78, 82, 58, 46, 102, 22, 106, 82, 46, 138, 106, 82, 166, 172, 178, 190, 106, 226, 82, 166, 238, 172, 178, 22, 106, 262, 190, 282, 22, 106, 310, 316, 226, 82, 166, 238, 172, 346, 46, 178, 22, 358, 22, 10, 366, 106, 262, 382, 82, 388, 58, 22, 22, 46, 418

Offset: 1

Author

Michel Marcus, Mar 29 2023

Keywords

• nonn

Comments

Let k be the least instance a(k) = m, then A329872(k) = m*A361058(m). For instance a(3)=10, and A329872(3) = 1100 = 10*110 = 10*A361058(10).

Can we get a(k)=30 or a(k)=52 (see A361058)?

Examples

			a(3)=10 because A329872(3)=1100 which can be expressed as 1*1100, 2*550, 4*275, 5*220, 10*110, ... where 10*110 is the first case where both factors are nontotients.
		

Links

• Michel Marcus, Table of n, a(n) for n = 1..7280

Crossrefs

Cf. A002202, A005277, A329872, A361058.

Programs

PARI

is(n) = if(!istotient(n), my(v=divisors(n)); for(i=1, (1+#v)\2, if(istotient(v[i])&&istotient(n/v[i]), return(1))); 0); \\ A329872
lista(nn) = for (n=1, nn, if (is(n), my(d=divisors(n)); for (i=1, (1+#d)\2, if (istotient(d[i]) && istotient(n/d[i]), print1(d[i], ", "); break););););