A326203 - OEIS

A326203

Lexicographically earliest sequence such that for all i, j, a(i) = a(j) => f(i) = f(j), where f(n) = 0 if n > 2 and gcd(n,phi(n)) = 1, with f(n) = n for all other numbers.

1, 2, 3, 4, 3, 5, 3, 6, 7, 8, 3, 9, 3, 10, 3, 11, 3, 12, 3, 13, 14, 15, 3, 16, 17, 18, 19, 20, 3, 21, 3, 22, 3, 23, 3, 24, 3, 25, 26, 27, 3, 28, 3, 29, 30, 31, 3, 32, 33, 34, 3, 35, 3, 36, 37, 38, 39, 40, 3, 41, 3, 42, 43, 44, 3, 45, 3, 46, 3, 47, 3, 48, 3, 49, 50, 51, 3, 52, 3, 53, 54, 55, 3, 56, 3, 57, 3, 58, 3, 59, 3, 60, 61, 62, 3, 63, 3, 64, 65, 66, 3, 67, 3

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OFFSET

1,2

COMMENTS

For all i, j:

A305801(i) = A305801(j) => a(i) = a(j),

a(i) = a(j) => A009195(i) = A009195(j) => A297086(i) = A297086(j),

a(i) = a(j) => A000001(i) = A000001(j) => A297086(i) = A297086(j).

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..65537

PROG

(PARI)

up_to = 65537;

rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om, invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om, invec[i], i); outvec[i] = u; u++ )); outvec; };

Aux326203(n) = if((n>2) && (1==gcd(n, eulerphi(n))), 0, n);

v326203 = rgs_transform(vector(up_to, n, Aux326203(n)));

A326203(n) = v326203[n];

CROSSREFS

Cf. A000001, A000010, A003277, A009195, A297086, A305801.

Cf. also A326201, A326202.

Sequence in context: A328470 A322810 A322024 * A355835 A305896 A322588

Adjacent sequences: A326200 A326201 A326202 * A326204 A326205 A326206

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jul 11 2019

STATUS

approved