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A089632
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1 + product of prime factors of n is a perfect square.
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3
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3, 9, 15, 27, 35, 45, 75, 81, 135, 143, 175, 195, 225, 243, 245, 255, 323, 375, 399, 405, 483, 585, 675, 729, 765, 875, 899, 975, 1023, 1125, 1155, 1197, 1215, 1225, 1275, 1295, 1443, 1449, 1573, 1599, 1715, 1755, 1763, 1859, 1875, 2025, 2187, 2295, 2535
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| The prime factors of 35 are 5 and 7 and 5 * 7 + 1 = 36 is a square; so 35 belongs to the sequence.
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MATHEMATICA
| ppf[n_] := Apply[Times, Transpose[FactorInteger[n]][[1]]]; Select[Range[2, 10^3], IntegerQ[Sqrt[ppf[ # ] + 1]] &]
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CROSSREFS
| Cf. A089653. A091278 gives squares, A091279 gives square roots.
Sequence in context: A138495 A055927 A087031 * A082897 A147516 A131822
Adjacent sequences: A089629 A089630 A089631 * A089633 A089634 A089635
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KEYWORD
| nonn
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AUTHOR
| Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Jan 04 2004
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EXTENSIONS
| More terms from Ray Chandler (rayjchandler(AT)sbcglobal.net), Jan 05 2004
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