A332839 Irregular triangle whose n-th row lists the integers x such that the number of nonprimes (i.e., 1 and composites) in the reduced residue set (RSS(x)) of x equals n, or 0 if there are no such x.

1, 2, 3, 4, 6, 8, 12, 18, 24, 30, 5, 10, 14, 20, 42, 60, 7, 9, 16, 36, 48, 90, 15, 22, 54, 84, 26, 28, 66, 120, 11, 21, 32, 40, 72, 78, 210, 13, 34, 50, 38, 44, 70, 150, 102, 114, 126, 17, 27, 46, 56, 96, 108, 180, 19, 33, 52, 132, 25, 45, 80, 168, 0, 23, 39, 58, 62, 110, 138

Offset: 1

Author

Michel Marcus, Feb 26 2020

Keywords

• nonn
• tabf

Examples

			Triangle begins:
1, 2, 3, 4, 6, 8, 12, 18, 24, 30;
5, 10, 14, 20, 42, 60;
7, 9, 16, 36, 48, 90;
15, 22, 54, 84;
26, 28, 66, 120;
11, 21, 32, 40, 72, 78, 210;
...
		

Links

• Abhijit A J, A. Satyanarayana Reddy, Number of non-primes in the set of units modulo n, arXiv:1907.09908 [math.GM], 2019. See p. 3.

Crossrefs

Cf. A048597 (1st row), A072022 (least x), A074915 (largest x), A076366 (row lengths).

Programs

Mathematica

t = Select[ Table[{ EulerPhi[n] - PrimePi[n] + PrimeNu[n], n}, {n, 2000}], #[[1]] <= 100 &]; c = Complement[Range[100], First /@ t]; Last /@ (Sort@ Join[ Transpose[{c, 0 c}], t]) (* Giovanni Resta, Feb 26 2020 *)