login
a(n) is the largest prime < A051451(n) - 1.
3

%I #18 Aug 27 2024 09:15:13

%S 3,7,53,409,829,2503,27701,360337,720703,12252197,232792501,

%T 5354228843,26771144371,80313433159,2329089562747,72201776446757,

%U 144403552893563,5342931457063157,219060189739591153,9419588158802421517,442720643463713815129

%N a(n) is the largest prime < A051451(n) - 1.

%C This is a companion to A058019.

%H Amiram Eldar, <a href="/A058023/b058023.txt">Table of n, a(n) for n = 3..377</a>

%e A051451(6) = 420, 420 - 1 = 419 is preceded by the prime 409, so a(6) = 409.

%t NextPrime[Rest@ FoldList[LCM, Select[Range[50], PrimePowerQ]] - 1, -1] (* _Amiram Eldar_, Aug 27 2024 *)

%Y Cf. A000961, A003418, A051451, A058019.

%K nonn

%O 3,1

%A _Labos Elemer_, Nov 15 2000

%E Edited by _N. J. A. Sloane_, Aug 20 2021