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A086806
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Sarrus numbers k such that k-1 and k+1 have the same number of prime divisors (counted with multiplicity).
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1
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341, 13747, 19951, 35333, 60787, 137149, 150851, 387731, 458989, 617093, 769757, 1104349, 1251949, 1277179, 1397419, 1463749, 1507963, 1826203, 2134277, 2205967, 2617451, 2976487, 3345773, 4361389, 6474691, 6955541, 8095447
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OFFSET
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1,1
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LINKS
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EXAMPLE
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341 is a pseudoprime to base 2 while 340 = 2^2*5*17 and 342 = 2*3^2*19 each have four primes dividing them.
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MATHEMATICA
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PrimeFactorExponentsAdded[n_] := Plus @@ Flatten[ Table[ # [[2]], {1}] & /@ FactorInteger[n]]; Select[ Range[9224390], !PrimeQ[ # ] && PowerMod[2, # - 1, # ] == 1 && PrimeFactorExponentsAdded[ # - 1] == PrimeFactorExponentsAdded[ # + 1] & ]
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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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