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A080864
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Numbers n such that spf(n)+2 = spf(n-2), where spf=A020639 (smallest prime factor).
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1
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27, 57, 87, 117, 147, 177, 205, 207, 237, 267, 297, 327, 357, 387, 415, 417, 447, 477, 507, 537, 567, 597, 625, 627, 657, 687, 717, 747, 777, 807, 835, 837, 867, 897, 927, 957, 987, 1017, 1045, 1047, 1077, 1107, 1137, 1167, 1197, 1227, 1255, 1257, 1287
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| (spf(n),spf(n-2)) are twin prime pairs.
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EXAMPLE
| 1921=17*113, 1921-2=1919=19*101 and (17,19)=(A001359(4), A006512(4)), therefore 1921 is a term: a(74)=1921, A080863(74)=1919.
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CROSSREFS
| Cf. A080863(n)=a(n)-2, A001359, A006512.
Sequence in context: A042456 A132768 A053180 * A039459 A157500 A180574
Adjacent sequences: A080861 A080862 A080863 * A080865 A080866 A080867
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KEYWORD
| nonn
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AUTHOR
| Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Feb 21 2003
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