A098466 - OEIS

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A098466

Numbers k such that N*2^k - 1 is prime where N = 9999999999999999999999988888888888888888887777777777777777766666666666665555555555544444443333322211.

86, 146, 806, 5010, 19338, 20210, 67278, 83406

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

9999999999999999999999988888888888888888887777777777777777766666666666665555555555544444443333322211 is a 100-digit prime that is easy to remember: 23 9's then 19 8's then 17 7's then 13 6's then 11 5's then 7 4's then 5 3's then 3 2's and 2 1's. Writing p(k) for prime(k), this is p(9)9 p(8)8 p(7)7 p(6)6 p(5)5 p(4)4 p(3)3 p(2)2 p(1)1.

Same number can be shortened as (10^100-(10^77+10^58+10^41+10^28+10^17+10^10+10^5-7)/9-12). (By David A. Corneth, original comment can be found in A098467)

a(7) > 22200. - Jinyuan Wang, Mar 19 2020

a(8) > 71000. - Daniel Suteu, Sep 04 2020

LINKS

Table of n, a(n) for n=1..8.

CROSSREFS

Cf. A098467.

Sequence in context: A095581 A097399 A039488 * A044256 A044637 A229359

Adjacent sequences: A098463 A098464 A098465 * A098467 A098468 A098469

KEYWORD

nonn,more,less

AUTHOR

Pierre CAMI, Sep 09 2004

EXTENSIONS

a(5)-a(6) from Jinyuan Wang, Mar 19 2020

a(7) from Daniel Suteu, Sep 04 2020

a(8) from Michael S. Branicky, Apr 06 2023

STATUS

approved