cp's OEIS Frontend

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

%I A337426 #8 Sep 02 2020 04:48:24
%S A337426 2,16,24,25,30,40,41,50,57,61,64,65,69,71,74,77,79,80,82,84,89,95,97,
%T A337426 99,104,105,106,107,111,112,119,124,129,132,133,136,137,139,141,143,
%U A337426 147,153,155,158,165,166,167,168,170,176,177,178,181,193,203,208,215,216
%N A337426 Sums s of positive exponents such that no prime of the form (3^j*5^k + 1)/2 with j + k = s exists.
%H A337426 Robert Israel, <a href="/A337426/b337426.txt">Table of n, a(n) for n = 1..800</a>
%p A337426 filter:= proc(n) local k, p;
%p A337426    for k from 1+(n-1 mod 2) to n-1 by 2 do
%p A337426      p:= (3^(n-k)*5^k+1)/2;
%p A337426      if isprime(p) then return false fi
%p A337426    od;
%p A337426    true
%p A337426 end proc:
%p A337426 select(filter, [$2..300]); # _Robert Israel_, Sep 01 2020
%Y A337426 Positions of 0 in A337425.
%Y A337426 Cf. A336772, A337424.
%K A337426 nonn
%O A337426 1,1
%A A337426 _Hugo Pfoertner_, Aug 27 2020