A267507 Prime numbers n such that n-1 is squarefree and all prime divisors of n-1 other than 19 are in the sequence.

2, 3, 7, 43, 4903, 168241543, 5773040306503

Offset: 1

Author

José María Grau Ribas, Jan 16 2016

Keywords

• nonn
• fini
• full

Crossrefs

Cf. A267503, A267504, A267505, A267506, A267507.

Programs

Mathematica

S[1] = {2, 19}; PR[S_] := Product[S[[i]], {i, Length[S]}];
S[m_] := S[m] =  Union[S[m - 1], Select[Table[PR[Subsets[S[m - 1]] [[i]]] + 1, {i, 2^Length[S[m - 1]]}], PrimeQ]]; A267507 = Complement[S[7], {19}]
(* S[7]=S[8] ==> sequence is finite and full; José María Grau Ribas, Nov 22 2021 *)