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A134601
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Nonprime numbers such that the square mean of their prime factors is a prime (where the square mean of c and d is sqrt((c^2+d^2)/2)).
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3
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1, 4, 8, 9, 16, 25, 27, 32, 49, 64, 81, 119, 121, 125, 128, 161, 169, 243, 256, 289, 343, 351, 361, 512, 529, 595, 625, 721, 729, 841, 845, 959, 961, 1024, 1045, 1081, 1241, 1323, 1331, 1369, 1375, 1547, 1681, 1792, 1849, 1855, 2048, 2187, 2197, 2209, 2401
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| All perfect prime powers (A025475) are included.
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EXAMPLE
| a(5)=25, since 25=5*5 and sqrt((5^2+5^2)/2)=5; a(13)=119, since 119=7*17 and sqrt((7^2+17^2)/2)=sqrt(169)=13.
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CROSSREFS
| Cf. A001597, A025475, A134333, A134344, A134376.
Cf. A134600, A134605, A134608, A134611, A134617, A134619, A134621.
Sequence in context: A080062 A088949 A134600 * A134611 A134612 A025475
Adjacent sequences: A134598 A134599 A134600 * A134602 A134603 A134604
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KEYWORD
| nonn
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AUTHOR
| Hieronymus Fischer (Hieronymus.Fischer(AT)gmx.de), Nov 11 2007
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