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Difference between LCM(1,...,x) and the smallest prime > LCM(1,...,x), where x is the n-th prime power (A000961).
1

%I #19 Aug 13 2024 05:30:33

%S 1,1,1,1,1,1,13,1,13,31,23,19,1,41,1,31,43,1,41,53,79,59,1,59,61,113,

%T 97,179,73,73,97,103,101,109,1,229,109,139,113,227,131,191,163,1,199,

%U 151,139,1,223,229,367,239,499,251,509,251,227,373,281,233,283,229,277,263

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

%C The first value corresponds to x = 1, LCM(1) = 1.

%C For the first 100 prime powers, the value is either prime or 1.

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

%F a(n) = A013632(A051451(n)) = A058017(n) - A051451(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) = 853-840 = 13.

%t With[{max = 250}, (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), v = lcm(vector(n, x, x)); print1(nextprime(v+1) - v, ", ")););} \\ _Michel Marcus_, Apr 09 2015

%Y Cf. A000961, A003418, A013632, A051451, A058017.

%K nonn

%O 1,7

%A _Labos Elemer_, Nov 14 2000

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

%E Offset set to 1 by _Michel Marcus_, Apr 09 2015

%E Name corrected by _Amiram Eldar_, Aug 13 2024