A227007 Numbers k such that k-1 is squarefree and every prime divisor of k-1 is in the sequence.

2, 3, 4, 7, 8, 15, 22, 43, 44, 87, 130, 259, 302, 603, 904, 1807

Offset: 1

Author

José María Grau Ribas, Jun 27 2013

Keywords

• nonn
• fini
• full

Comments

The complement of A227006.

1807 is the last term in this sequence. - Charles R Greathouse IV, Jun 27 2013

Links

• J. M. Grau, A. M. Oller-Marcén and J, Sondow, On the congruence 1^n+2^n+...+n^n == d (mod n), where d divides n, arXiv preprint arXiv:1309.7941, 2013

Crossrefs

Cf. A227006.

Programs

Mathematica

Needs["NumberTheory`NumberTheoryFunctions`"];Is[2] = True; Is[{}] = True; Is[n_] := Is[n] = If[ListQ[n], Is[n[[1, 1]]] && Is[Rest[n]], SquareFreeQ[n - 1] && Is[fa[n - 1]]]; Select[1 + Range@10000, Is]