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Search: id:A074491
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| A074491 |
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"Squarefree" primes: primes without squares in their decimal expansion. |
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+0
1
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| 2, 3, 5, 7, 23, 37, 53, 67, 73, 83, 223, 227, 233, 263, 277, 283, 337, 353, 373, 383, 523, 557, 563, 577, 587, 653, 673, 677, 683, 727, 733, 757, 773, 787, 823, 827, 853, 857, 863, 877, 883, 887, 2237, 2267, 2273, 2287, 2333, 2357, 2377, 2383, 2633, 2657
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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The usual definition of "squarefree number" means that there is no square as factor of the number, but we consider "squarefree number" as without any square in its decimal expansion (or representation). The procedure "omit numbers with squares in their decimal expansion" is rather severe: from 500 first primes only 68 survive and are in the sequence, while all primes are squarefree in usual sence!
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EXAMPLE
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3557 is a member because it has no squares 0, 1, 4, 9, 16, 25, 36 in its decimal expansion; 3253 is a prime but contains the square 25 so it is not a member.
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CROSSREFS
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Sequence in context: A113611 A038925 A154761 this_sequence A154385 A125525 A019546
Adjacent sequences: A074488 A074489 A074490 this_sequence A074492 A074493 A074494
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KEYWORD
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easy,nonn,base
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Sep 26 2002
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