A337426 Sums s of positive exponents such that no prime of the form (3^j*5^k + 1)/2 with j + k = s exists.

2, 16, 24, 25, 30, 40, 41, 50, 57, 61, 64, 65, 69, 71, 74, 77, 79, 80, 82, 84, 89, 95, 97, 99, 104, 105, 106, 107, 111, 112, 119, 124, 129, 132, 133, 136, 137, 139, 141, 143, 147, 153, 155, 158, 165, 166, 167, 168, 170, 176, 177, 178, 181, 193, 203, 208, 215, 216

Offset

1,1

Links

Robert Israel, Table of n, a(n) for n = 1..800

Maple

filter:= proc(n) local k, p;
   for k from 1+(n-1 mod 2) to n-1 by 2 do
     p:= (3^(n-k)*5^k+1)/2;
     if isprime(p) then return false fi
   od;
   true
end proc:
select(filter, [$2..300]); # Robert Israel, Sep 01 2020

Crossrefs

Positions of 0 in A337425.

Cf. A336772, A337424.

Sequence in context: A330611 A228158 A330662 * A295822 A212765 A343839

Adjacent sequences: A337423 A337424 A337425 * A337427 A337428 A337429

Keyword

nonn

Author

Hugo Pfoertner, Aug 27 2020

Status

approved