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A252020 Odd perfect powers n not congruent to 1 mod 6 such that n*4^k - 1 has a covering set. 0
56169, 651249, 20985561, 1054235961, 1688470281, 3718682361, 3923393769, 4013349201, 5866487649, 6557598441, 7121165769, 7232992209, 8527229649, 8764891641, 9387865881, 10441365489, 12922915041, 15279184881, 17063935641, 19501284609, 19760206041 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If a(n) is a square, then for all k >= 1 the numbers a(n)*4^k - 1 have at least three distinct prime factors.

LINKS

Table of n, a(n) for n=1..21.

CROSSREFS

Sequence in context: A022224 A230336 A252320 * A031655 A203964 A198165

Adjacent sequences: A252017 A252018 A252019 * A252021 A252022 A252023

KEYWORD

nonn

AUTHOR

Arkadiusz Wesolowski, Dec 15 2014

STATUS

approved

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Last modified February 1 19:57 EST 2023. Contains 359995 sequences. (Running on oeis4.)