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A189991
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Numbers with prime factorization p^4*q^4.
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2
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1296, 10000, 38416, 50625, 194481, 234256, 456976, 1185921, 1336336, 1500625, 2085136, 2313441, 4477456, 6765201, 9150625, 10556001, 11316496, 14776336, 17850625, 22667121, 29986576, 35153041, 45212176, 52200625, 54700816, 57289761, 68574961, 74805201
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OFFSET
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1,1
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COMMENTS
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The primes p and q must be distinct, or else the product has factorization p^8 (or q^8, for that matter).
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LINKS
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T. D. Noe, Table of n, a(n) for n = 1..1000
Will Nicholes, Prime Signatures
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MATHEMATICA
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lst = {}; Do[If[Sort[Last/@FactorInteger[n]] == {4, 4}, Print[n]; AppendTo[lst, n]], {n, 55000000}]; lst (* Orlovsky *)
lim = 10^8; pMax = PrimePi[(lim/16)^(1/4)]; Select[Union[Flatten[Table[Prime[i]^4 Prime[j]^4, {i, 2, pMax}, {j, i - 1}]]], # <= lim &] (* From Alonso del Arte, May 03 2011 *)
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PROG
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(PARI) list(lim)=my(v=List(), t); forprime(p=2, lim^(1/8), t=p^4; forprime(q=p+1, (lim\t)^(1/4), listput(v, t*q^4))); vecsort(Vec(v)) \\ Charles R Greathouse IV, Jul 24 2011
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CROSSREFS
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Cf. A137488, A179671, A189990.
Sequence in context: A217908 A223508 A137488 * A221006 A016864 A064785
Adjacent sequences: A189988 A189989 A189990 * A189992 A189993 A189994
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KEYWORD
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nonn,changed
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AUTHOR
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Vladimir Joseph Stephan Orlovsky, May 03 2011
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STATUS
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approved
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