A217035 Generalized cuban primes (A007645) which are also Class 1- (or Pierpont) primes (A005109).

3, 7, 13, 19, 37, 73, 97, 109, 163, 193, 433, 487, 577, 769, 1153, 1297, 1459, 2593, 2917, 3457, 3889, 10369, 12289, 17497, 18433, 39367, 52489, 139969, 147457, 209953, 331777, 472393, 629857, 746497, 786433, 839809, 995329, 1179649, 1492993, 1769473

Offset: 1

Author

Jonathan Vos Post, Sep 24 2012

Keywords

• nonn
• easy

Comments

Is this the union of A058383 and {3}? - R. J. Mathar, Sep 28 2012

Yes, it is, because the only Fermat prime == 0 or 1 mod 3 is 3. - Robert Israel, Mar 02 2018

Generalized cuban primes are primes of the form x^2 + xy + y^2; or: primes of form x^2 + 3*y^2; or: primes == 0 or 1 mod 3. Class 1- (or Pierpont) primes: primes of the form 2^t*3^u + 1.

Links

• Ray Chandler, Table of n, a(n) for n = 1..8379 (terms < 10^1000)

Crossrefs

Cf. A007645, A005109, A058383.

Programs

Mathematica

nn = 100000; t1 = Join[{3}, Select[Prime[Range[nn]], MemberQ[{1}, Mod[#, 3]] &]]; t2 = Select[Prime[Range[nn]], Max @@ First /@ FactorInteger[# - 1] < 5 &]; Intersection[t1, t2] (* T. D. Noe, Sep 26 2012 *)

Formula

A007645 INTERSECTION A005109.