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

1,2

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

Prog

(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];

Crossrefs

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

Cf. A017665, A017666, A074902, A094759.

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

Sequence in context: A338497 A137317 A308702 * A094759 A214701 A030542

Adjacent sequences: A326197 A326198 A326199 * A326201 A326202 A326203

Keyword

nonn

Author

Antti Karttunen, Jun 13 2019

Status

approved