A278342 Zero terms of A278341

1, 2, 3, 4, 5, 7, 32, 52, 55, 56, 58, 61, 64, 66, 72, 80, 86, 88, 89, 94, 101, 103, 108, 109, 128, 130, 131, 161, 173, 187, 193, 194, 213, 214, 224, 244, 253, 260, 270, 292, 304, 314, 323, 334, 344, 348, 349, 365, 370, 373, 388, 404, 424, 454, 470, 478, 482

Offset

1,2

Comments

It is conjectured that this sequence is finite and all 208 terms are found.

Links

Lei Zhou, Table of n, a(n) for n = 1..208

Example

A278341(1,2,3,4,5,7)=0, so a(1)=1, a(2)=2,...,a(5)=5, and a(6)=7.
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...}.

Mathematica

p = 3; sp = {p}; m = 0; Table[
While[m++; l = Length[sp];
  While[sp[[l]] < m,
   While[p = NextPrime[p];
    cp = 2*3^(Floor[Log[3, 2*p - 1]]) - p; ! PrimeQ[cp]];
   AppendTo[sp, p]; l++]; c = 2 - Mod[m + 1, 2]; ct = 0;
  Do[If[MemberQ[sp, m - c*sp[[i]]],
    If[Abs[Floor[Log[3, 2*sp[[i]] - 1]] -
        Floor[Log[3, 2*(m - c*sp[[i]]) - 1]]] <= 1,
     If[c == 1, If[(2*sp[[i]]) <= m, ct++], ct++]]], {i, 1, l}];
  ct > 0];
m, {n, 1, 208}]

Crossrefs

Cf. A278341, A274987.

Sequence in context: A063738 A063737 A338121 * A276522 A135709 A263043

Adjacent sequences: A278339 A278340 A278341 * A278343 A278344 A278345

Keyword

nonn,fini,full

Author

Lei Zhou, Nov 18 2016

Status

approved