A233552 - OEIS

A233552

Odd integers k such that for every m >= 1 the numbers k*4^m - 1 have at least three prime factors, not necessarily distinct, and k*4^m - 1 has at least two-element covering set.

361, 919, 1681, 1849, 2419, 2629, 3301, 5209, 5539, 5581, 6421, 7771, 8551, 9109, 9871, 10039, 10609, 10819, 11491, 13399, 13729, 13771, 14611, 15661, 15961, 16741, 17299, 18061, 18229, 18799, 19009, 19681, 21589, 21919, 21961, 22801, 24151, 24931, 25489

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OFFSET

1,1

COMMENTS

Here an n-element covering set is a minimal set of n distinct primes such that at least one of these primes divides every integer in the sequence k*4^m - 1, m >= 1. - Arkadiusz Wesolowski, Jul 21 2021

LINKS

Table of n, a(n) for n=1..39.

CROSSREFS

Sequence in context: A219340 A183997 A211822 * A176899 A361704 A302229

Adjacent sequences: A233549 A233550 A233551 * A233553 A233554 A233555

KEYWORD

nonn

AUTHOR

Arkadiusz Wesolowski, Dec 12 2013

EXTENSIONS

Name corrected by Arkadiusz Wesolowski, Jul 21 2021

STATUS

approved