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A076366
Number of numbers for which the count of nonprimes (i.e., 1 and composites) in their reduced residue set equals n.
4
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
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
KEYWORD
nonn
AUTHOR
Labos Elemer, Oct 10 2002
STATUS
approved