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Search: id:A164517
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| 4357, 12101, 16901, 28901, 52901, 164837, 184901, 220901, 224677, 417317, 427717, 682277, 792101, 820837, 894917, 972197, 1020101, 1110917, 1136357, 1144901, 1223237, 1313317, 1552517, 1887877, 1943237, 1976837, 2056357, 2464901
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OFFSET
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1,1
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COMMENT
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Primes p such that p-1 equals the square of a product of three distinct primes.
Primes of the similar form A162143(k)-1 do not exist, because A162143 are squares
which allows for the obvious factorization A162143(k)-1 = (A007304(k)+1)*(A007304(k)-1).
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EXAMPLE
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For p=4357=a(1), p=14356=2^2*3^2*11^2. For p=12101, p=1=12100=2^2*5^2*11^2.
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MATHEMATICA
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f[n_]:=FactorInteger[n][[1, 2]]==2&&Length[FactorInteger[n]]==3&&FactorInteger[n][[2, 2]]==2&&FactorInteger[n][[3, 2]]==2; lst={}; Do[p=Prime[n]; If[f[p-1], AppendTo[lst, p]], {n, 2, 9!}]; lst
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CROSSREFS
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Sequence in context: A068292 A154084 A031654 this_sequence A125825 A031564 A140937
Adjacent sequences: A164514 A164515 A164516 this_sequence A164518 A164519 A164520
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KEYWORD
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nonn
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AUTHOR
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Vladimir Orlovsky (4vladimir(AT)gmail.com), Aug 14 2009
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EXTENSIONS
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Edited by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 18 2009
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