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A128898 Primes of form 2^j + 2^k - 1 or 2^j + 2^k + 1.

%I A128898 #11 Jun 13 2018 23:09:55
%S A128898 2,3,5,7,11,13,17,19,23,31,37,41,47,67,71,73,79,97,127,131,137,191,
%T A128898 193,257,263,271,383,521,577,641,769,1031,1033,1039,1087,1151,1153,
%U A128898 1279,2053,2063,2081,2111,2113,4099,4111,4127,4129,4159,5119,6143,8191,8209
%N A128898 Primes of form 2^j + 2^k - 1 or 2^j + 2^k + 1.
%C A128898 Union of A000668, A081091 and A239712. - _Robert Israel_, Jun 13 2018
%H A128898 Robert Israel, <a href="/A128898/b128898.txt">Table of n, a(n) for n = 1..6772</a>
%e A128898 2^2 + 2^5 + 1 = 4 + 32 + 1 = 37 is prime, hence 37 is a term.
%e A128898 2^4 + 2^5 - 1 = 16 + 32 - 1 = 47 is prime, hence 47 is a term.
%e A128898 2^3 + 2^6 + 1 = 8 + 64 + 1 = 73 is prime, hence 73 is a term.
%p A128898 sort(convert(select(isprime, {2,seq(seq(seq(2^i+2^j+k,k=[-1,1]),j=1..i),i=1..15)}),list)); # _Robert Israel_, Jun 13 2018
%t A128898 lst = {}; Do[p = 2^a + 2^b; If[PrimeQ[p - 1], AppendTo[lst, p - 1]]; If[PrimeQ[p + 1], AppendTo[lst, p + 1]], {a, 0, 14}, {b, 0, a}]; Union@ lst (* _Robert G. Wilson v_ *)
%o A128898 (PARI) {m=13; v=[]; for(j=0, m, for(k=j, m, if(isprime(p=2^j+2^k-1), v=concat(v, p)); if(isprime(p=2^j+2^k+1), v=concat(v,p)))); w=Vec(listsort(List(v), 1)); w} /* _Klaus Brockhaus_, Apr 22 2007 */
%Y A128898 Cf. A000668 (Mersenne primes), A092506 (primes of form 2^n + 1), A070739 (primes of form 2^x+2^y+1), A081091, A239712.
%K A128898 nonn
%O A128898 1,1
%A A128898 _J. M. Bergot_, Apr 21 2007
%E A128898 Edited, corrected and extended by _Klaus Brockhaus_ and _Robert G. Wilson v_, Apr 22 2007