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A182262 Least prime p that 6^n - p is prime.

%I A182262 #20 Nov 05 2020 19:22:33
%S A182262 3,5,5,5,17,7,17,7,7,7,59,19,17,13,7,19,137,13,19,7,23,97,19,89,17,
%T A182262 223,29,109,5,19,5,59,197,5,17,307,59,83,109,157,19,23,43,109,103,7,
%U A182262 23,19,7,269,43,13,5,67,89,83,479,53,53,383,7,83,113,37,5,23
%N A182262 Least prime p that 6^n - p is prime.
%H A182262 Robert Israel, <a href="/A182262/b182262.txt">Table of n, a(n) for n = 1..2035</a>
%e A182262 For n=3 p=5 is the least prime that 6^3-p is prime (211).
%p A182262 f:= proc(n) local t,p;
%p A182262   t:= 6^n;
%p A182262   p:= 2;
%p A182262   do
%p A182262     p:= nextprime(p);
%p A182262   until isprime(t-p);
%p A182262   p
%p A182262 end proc:
%p A182262 map(f, [$1..100]); # _Robert Israel_, Nov 05 2020
%t A182262 f[n_] := Block[{p = 2}, While[! PrimeQ[6^n - p], p = NextPrime[p]];
%t A182262   p]; Array[f, 60]
%o A182262 (PARI) a(n) = my(p = 2); while(!isprime(6^n-p), p = nextprime(p+1)); p; \\ _Michel Marcus_, Mar 23 2016
%Y A182262 Cf. A013607, A059614 (n such that a(n)=5).
%K A182262 nonn
%O A182262 1,1
%A A182262 _Mateusz Szymański_, Apr 21 2012