A350319 - OEIS

%I #13 Jul 19 2024 08:47:15

%S 1,10,46,66,78,106,126,138,150,166,178,190,210,226,262,268,270,306,

%T 346,358,366,372,378,382,418,430,442,466,478,490,506,522,546,570,586,

%U 598,606,630,646,676,682,718,726,738,750,786,810,822,826,838,882,886,906

%N Totient numbers k such that 9*k is a nontotient.

%H Amiram Eldar, <a href="/A350319/b350319.txt">Table of n, a(n) for n = 1..10000</a>

%e 10 is a term since 10 = phi(11) = phi(22), but phi(n) = 9*10 = 90 has no solution.

%e 46 is a term since 46 = phi(47) = phi(94), but phi(n) = 9*46 = 414 has no solution.

%o (PARI) isA350319(n) = istotient(n) && !istotient(9*n)

%Y Totient numbers k such that m*k is a nontotient: A350316 (m=3), A350317 (m=5), A350318 (m=7), this sequence (m=9), A350320 (m=10), A350321 (m=14).

%Y Cf. A002202, A005277.

%K nonn

%O 1,2

%A _Jianing Song_, Dec 24 2021