A013607 - OEIS

%I #16 May 28 2023 16:26:55

%S 1,5,5,5,17,7,17,7,7,7,59,19,17,13,7,19,49,13,19,7,23,35,19,89,17,119,

%T 29,55,5,19,5,59,85,5,17,35,59,83,49,115,19,23,43,109,103,7,23,19,7,

%U 245,43,13,5,55,89,83,143,53,53,383,7,55,113,37,5,23,143,115

%N a(n) = 6^n-prevprime(6^n).

%H Daniel Starodubtsev, <a href="/A013607/b013607.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A000400(n) - A104091(n). - _Michel Marcus_, Jan 13 2020

%p seq(6^i-prevprime(6^i),i=1..100);

%t pp[n_]:=Module[{n6=6^n},n6-NextPrime[n6,-1]]; Array[pp,70] (* _Harvey P. Dale_, May 04 2011 *)

%t #-NextPrime[#,-1]&/@(6^Range[70]) (* _Harvey P. Dale_, May 28 2023 *)

%Y Cf. A000400 (6^n), A104091 (largest prime <= 6^n).

%K nonn

%O 1,2

%A James Kilfiger (mapdn(AT)csv.warwick.ac.uk)