A076366 Number of numbers for which the count of nonprimes (i.e., 1 and composites) in their reduced residue set equals n.

10, 6, 6, 4, 4, 7, 3, 4, 3, 7, 4, 4, 0, 6, 5, 1, 4, 3, 7, 4, 7, 2, 3, 3, 2, 2, 6, 5, 2, 2, 0, 6, 4, 3, 5, 4, 5, 3, 1, 3, 3, 4, 4, 6, 2, 3, 1, 6, 1, 6, 3, 6, 1, 4, 4, 4, 1, 1, 3, 6, 3, 2, 4, 4, 1, 1, 2, 4, 6, 0, 3, 4, 3, 5, 4, 1, 2, 8, 2, 5, 6, 2, 2, 5, 1, 4, 2, 4, 7, 2, 1, 2, 6, 1, 3, 5, 2, 3, 5, 3

Offset

1,1

Links

Giovanni Resta, Table of n, a(n) for n = 1..10000

Formula

a(n) = Card{x; A048864(x) = n}; a(n)=0 if supposedly no such number exists (see A072023).

Example

A048864(x) = 13: S = {},                                a(13) =  0;
A048864(x) = 16: S = {144},                             a(16) =  1;
A048864(x) = 22: S = {57,92},                           a(22) =  2;
A048864(x) = 7:  S = {13,34,50},                        a(7)  =  3;
A048864(x) = 4:  S = {15,22,54,84},                     a(4)  =  4;
A048864(x) = 15: S = {35,64,68,156,240},                a(15) =  5;
A048864(x) = 2:  S = {5,10,14,20,42,60},                a(2)  =  6;
A048864(x) = 6:  S = {11,21,32,40,72,78,210},           a(6)  =  7;
A048864(x) = 78: S = {133,177,268,440,490,552,870,990}, a(78) =  8;
A048864(x) = 1:  S = {1,2,3,4,6,8,12,18,24,30},         a(1)  = 10; See A048597.

Prog

(PARI) listn(nn) = {my(v = vector(10^5, n, eulerphi(n) - (primepi(n) - omega(n)))); vector(nn, k, if (#(w=Vec(select(x->(x==k), v, 1))) == 0, 0, #w)); } \\ Michel Marcus, Feb 23 2020

Crossrefs

Cf. A000010, A000720, A001221, A048597, A048864, A048865, A070971, A072022, A072023, A074915.

Sequence in context: A193952 A158508 A102690 * A304879 A105155 A072930

Adjacent sequences: A076363 A076364 A076365 * A076367 A076368 A076369

Keyword

nonn

Author

Labos Elemer, Oct 10 2002

Status

approved