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a(n) is the smallest prime > LCM(1,...,x), where x is the n-th prime power (A000961).
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%I #16 Aug 13 2024 05:29:54

%S 2,3,7,13,61,421,853,2521,27733,360391,720743,12252259,232792561,

%T 5354228921,26771144401,80313433231,2329089562843,72201776446801,

%U 144403552893641,5342931457063253,219060189739591279,9419588158802421659,442720643463713815201,3099044504245996706459

%N a(n) is the smallest prime > LCM(1,...,x), where x is the n-th prime power (A000961).

%C For the first 100 prime powers, the difference between a(n) and the LCM is either 1 or a prime.

%C The values of x are taken to be prime powers so that each distinct LCM occurs exactly once.

%F a(n) = A151800(A051451(n)) = A051451(n) + A058018(n). - _Amiram Eldar_, Aug 13 2024

%e The 6th distinct prime power is A000961(7) = 8, LCM(1,...,8) = 840 and 853 is the first prime that follows, thus a(7) = 853.

%t With[{max = 50}, NextPrime[Exp[Accumulate[Join[{0}, Select[Array[MangoldtLambda, max], # > 0 &]]]]]] (* _Amiram Eldar_, Aug 13 2024 *)

%o (PARI) lista(nn) = {for (n=1, nn, if ((n==1) || isprimepower(n), print1(nextprime(lcm(vector(n, x, x)) + 1), ", ")));} \\ _Michel Marcus_, Apr 09 2015

%Y Cf. A000961, A003418, A051451, A058018, A151800.

%K nonn

%O 1,1

%A _Labos Elemer_, Nov 14 2000

%E Edited by _Franklin T. Adams-Watters_, Aug 15 2006

%E Offset changed to 1 and more terms from _Michel Marcus_, Apr 09 2015

%E Name corrected by _Amiram Eldar_, Aug 13 2024