A229290 n is in the sequence if n is prime, (n-1)/3^A007949(n-1) is a squarefree number, A007949(n-1) < 3 and every prime divisor of n-1 is in the sequence.

2, 3, 7, 19, 43, 127, 2287, 4903, 5419, 13723, 14479, 82339, 98299, 101347, 304039, 617767, 688087, 1676827, 3735583, 3736087, 4130323, 4324363, 4693267, 4951819, 10621603, 11032999, 11208259, 11554243, 11737783, 12198859, 26152603, 26563939, 28159603

Offset

1,1

Comments

If n is in A226961 then n is some product of elements of this sequence.

Links

Table of n, a(n) for n=1..33.

Mathematica

fa = FactorInteger; free[n_] := n == Product[fa[n][[i, 1]], {i,
  Length[fa[ n]]}]; Os[b_, 1] = True; Os[b_, 2] = True; Os[b_, b_] = True; Os[b_, n_] := Os[b, n] = PrimeQ[n] && free[(n-1)/ b^IntegerExponent[n - 1,  b]] && IntegerExponent[n - 1, b] < 3 && Union@Table[Os[b, fa[n - 1][[i, 1]]], {i, Length[fa[n - 1]]}] == {True}; G[b_] := Select[Prime[Range[2000]], Os[b, #] &]; G[3]

Crossrefs

Cf. A007949, A226961, A229289, A229291.

Sequence in context: A257551 A091410 A069051 * A246033 A122724 A256758

Adjacent sequences: A229287 A229288 A229289 * A229291 A229292 A229293

Keyword

nonn

Author

José María Grau Ribas, Oct 05 2013

Status

approved