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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
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.
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
KEYWORD
nonn
AUTHOR
STATUS
approved