A336554 - OEIS

A336554

Odd numbers k such that rad(k) divides sigma(k).

1, 135, 891, 1521, 3375, 5733, 10935, 11907, 41067, 43875, 84375, 89667, 92781, 98865, 107811, 108927, 154791, 185625, 200655, 216513, 226233, 273375, 274625, 287469, 307125, 336141, 416745, 448335, 480249, 544635, 557375, 570375, 590625, 627669, 628849, 648675, 692055, 823875, 885735, 931095, 968877, 1071875, 1108809, 1131165

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OFFSET

1,2

COMMENTS

Only a minority of terms seem to be also in A228058: 5733, 92781, 2069613, 3341637, 4179357, 5929605, 60998353, 67637349, 89162541 among the first 216, the five of them which occur also in A263983.

Question: Is the intersection with A336553 empty?

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..1200 (terms 1..216 from Antti Karttunen)

Index entries for sequences where odd perfect numbers must occur, if they exist at all.

PROG

(PARI) isA336554(n) = if(!(n%2), 0, !(sigma(n) % factorback(factorint(n)[, 1])));

CROSSREFS

Odd terms of A175200.

Cf. A000203, A007947, A228058, A263983.

Cf. also A336553.

Sequence in context: A362400 A211680 A212610 * A238330 A358002 A157734

Adjacent sequences: A336551 A336552 A336553 * A336555 A336556 A336557

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jul 28 2020

STATUS

approved