A326200 Lexicographically earliest sequence such that a(i) = a(j) => sigma(i)/i = sigma(j)/j for all i, j.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 6, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90

Offset: 1

Author

Antti Karttunen, Jun 13 2019

Keywords

• nonn

Comments

Restricted growth sequence transform of the abundancy index of n.

For all i, j:

a(i) = a(j) <=> A094759(i) = A094759(j),

a(i) = a(j) => A017665(i) = A017665(j),

a(i) = a(j) => A017666(i) = A017666(j).

Links

• Antti Karttunen, Table of n, a(n) for n = 1..105664
• Achim Flammenkamp, The Multiply Perfect Numbers Page

Crossrefs

Cf. A000396 (positions of 6's), A005820 (positions of 119's).

Cf. A017665, A017666, A074902, A094759.

Cf. A218406, A218407, A218408, A218427, A326202.

Programs

PARI

up_to = 105664; \\ (In the same equivalence class as 78, 364 and 6448).
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; };
v326200 = rgs_transform(vector(up_to,n,sigma(n)/n));
A326200(n) = v326200[n];