cp's OEIS Frontend

A278342 Zero terms of A278341.

%I A278342 #7 Jun 02 2025 12:20:14
%S A278342 1,2,3,4,5,7,32,52,55,56,58,61,64,66,72,80,86,88,89,94,101,103,108,
%T A278342 109,128,130,131,161,173,187,193,194,213,214,224,244,253,260,270,292,
%U A278342 304,314,323,334,344,348,349,365,370,373,388,404,424,454,470,478,482
%N A278342 Zero terms of A278341.
%C A278342 It is conjectured that this sequence is finite and all 208 terms are found.
%H A278342 Lei Zhou, <a href="/A278342/b278342.txt">Table of n, a(n) for n = 1..208</a>
%e A278342 A278341(1,2,3,4,5,7)=0, so a(1)=1, a(2)=2,...,a(5)=5, and a(6)=7.
%e A278342 a(7)=32 is because 32 cannot be decomposited into the sum of two terms in A274987={3, 5, 7, 11, 13, 17, 23, 31, 37, 53, 59, 61, 73, 79, 83, 89, 101, 103, 109...}.
%t A278342 p = 3; sp = {p}; m = 0; Table[
%t A278342 While[m++; l = Length[sp];
%t A278342   While[sp[[l]] < m,
%t A278342    While[p = NextPrime[p];
%t A278342     cp = 2*3^(Floor[Log[3, 2*p - 1]]) - p; ! PrimeQ[cp]];
%t A278342    AppendTo[sp, p]; l++]; c = 2 - Mod[m + 1, 2]; ct = 0;
%t A278342   Do[If[MemberQ[sp, m - c*sp[[i]]],
%t A278342     If[Abs[Floor[Log[3, 2*sp[[i]] - 1]] -
%t A278342         Floor[Log[3, 2*(m - c*sp[[i]]) - 1]]] <= 1,
%t A278342      If[c == 1, If[(2*sp[[i]]) <= m, ct++], ct++]]], {i, 1, l}];
%t A278342   ct > 0];
%t A278342 m, {n, 1, 208}]
%Y A278342 Cf. A278341, A274987.
%K A278342 nonn,fini,full
%O A278342 1,2
%A A278342 _Lei Zhou_, Nov 18 2016