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A087521
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Smallest prime p such that the prime signature of p+1 has not occurred earlier.
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2
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2, 3, 5, 7, 11, 23, 29, 31, 47, 59, 71, 127, 167, 179, 191, 223, 239, 359, 383, 389, 419, 431, 479, 719, 839, 863, 971, 1151, 1259, 1279, 1439, 1511, 2111, 2309, 2591, 2687, 2699, 2879, 3023, 3119, 3359, 3583, 3779, 5039, 5119, 5399, 6047, 6143, 6299, 6719
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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sig[n_] := Sort @ FactorInteger[n][[;; , 2]]; seq = {}; sigs = {}; Do[If[PrimeQ[p] && !MemberQ[sigs, (s = sig[p + 1])], AppendTo[seq, p]; AppendTo[sigs, s]], {p, 2, 7000}]; seq (* Amiram Eldar, Dec 30 2020 *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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