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A124190 a(n) is the largest prime < 4*a(n-1) for n > 1, with a(1) = 2.

%I A124190 #12 Dec 19 2024 15:06:02
%S A124190 2,7,23,89,353,1409,5623,22483,89923,359663,1438643,5754571,23018273,
%T A124190 92073083,368292317,1473169213,5892676849,23570707387,94282829533,
%U A124190 377131318127,1508525272477,6034101089897,24136404359569,96545617438253,386182469752993,1544729879011951
%N A124190 a(n) is the largest prime < 4*a(n-1) for n > 1, with a(1) = 2.
%H A124190 Artur Jasinski, Dec 16 2006, <a href="/A124190/b124190.txt">Table of n, a(n) for n = 1..40</a>
%t A124190 NestList[NextPrime[4#,-1]&,2,30] (* _Harvey P. Dale_, Oct 11 2023 *)
%Y A124190 Cf. A126031.
%K A124190 nonn
%O A124190 1,1
%A A124190 _Artur Jasinski_, Dec 16 2006