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A067386
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Primes p such that p+1 and p-1 have the same number of distinct prime factors.
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4
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3, 11, 13, 19, 23, 37, 47, 53, 73, 97, 107, 131, 139, 163, 181, 193, 229, 239, 281, 307, 311, 349, 373, 379, 383, 409, 439, 443, 487, 491, 521, 577, 599, 601, 617, 619, 643, 683, 701, 709, 727, 739, 743, 761, 811, 821, 827, 829, 853, 863, 881, 883, 919, 937
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OFFSET
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1,1
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LINKS
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MAPLE
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q:= p-> isprime(p) and nops(ifactors(p+1)[2])=nops(ifactors(p-1)[2]):
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MATHEMATICA
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Select[Prime[Range[200]], PrimeNu[#-1]==PrimeNu[#+1]&] (* Harvey P. Dale, Jun 28 2020 *)
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PROG
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CROSSREFS
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Cf. A115103 (same number of prime factors with multiplicity).
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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