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A326200 Lexicographically earliest sequence such that a(i) = a(j) => sigma(i)/i = sigma(j)/j for all i, j. 4
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 (list; graph; refs; listen; history; text; internal format)
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: A318893 A137317 A308702 * A094759 A214701 A030542

Adjacent sequences:  A326197 A326198 A326199 * A326201 A326202 A326203

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jun 13 2019

STATUS

approved

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Last modified April 5 00:43 EDT 2020. Contains 333238 sequences. (Running on oeis4.)