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A283622 a(n) = smallest k > n + 1 not of the form p + n^x with p prime, where gcd(k, n) = 1 and gcd(k-1, n-1) = 1. 1

%I #9 Sep 08 2022 08:46:18

%S 127,328,149,26,127,254,17,34,59,50,37,134,23,136,65,26,43,96,29,142,

%T 47,50,49,116,35,52,53,56,79,122,41,58,59,92,157,86,47,64,89,50,67,

%U 186,53,94,95,56,73,134,59,100,77,78,79,146,65,82,83,86,109,204,71

%N a(n) = smallest k > n + 1 not of the form p + n^x with p prime, where gcd(k, n) = 1 and gcd(k-1, n-1) = 1.

%o (Magma) lst:=[]; for n in [2..62] do k:=n+2; t:=0; while t eq 0 do if GCD(k, n) eq 1 and GCD(k-1, n-1) eq 1 then x:=-1; repeat x+:=1; p:=k-n^x; until p lt 2 or IsPrime(p); if p lt 2 then Append(~lst, k); t:=1; end if; end if; k+:=1; end while; end for; lst;

%Y Cf. A006285, A282430.

%K nonn

%O 2,1

%A _Arkadiusz Wesolowski_, Mar 12 2017

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Last modified April 25 11:21 EDT 2024. Contains 371967 sequences. (Running on oeis4.)