A328418 Records in A328412.

2, 4, 7, 11, 12, 13, 15, 16, 23

Offset: 1

Author

Jianing Song, Oct 14 2019

Keywords

• nonn
• hard
• more

Comments

Companion sequence of A328417.

Conjecture: this sequence is infinite. That is to say, A328412 is unbounded.

Examples

			Let (Z/mZ)* be the multiplicative group of integers modulo m. We have (Z/mZ)* = C_2 X C_60 has 11 solutions, namely m = 143, 155, 175, 183, 225, 244, 286, 310, 350, 366, 450; for all k' < 30, (Z/mZ)* = C_2 X C_(2k') has fewer than 11 solutions. So A328412(30) = 11 is a term.
		

Links

• Wikipedia, Multiplicative group of integers modulo n

Crossrefs

Cf. A328412, A328417.

Programs

PARI

my(t=0); for(k=1, 5000, if(A328412(k)>t, print1(a(k), ", "); t=A328412(k)))