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Search: id:A127913
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| 3, 0, 2, 1, 6, 1, 7, 2, 2, 9, 10, 1, 6, 1, 9, 6, 2, 9, 6, 2, 1, 11, 6, 9, 2, 3, 1, 22, 5, 18, 2, 9, 10, 1, 18, 5, 10, 1, 14, 13, 6, 18, 5, 18, 1, 10, 15, 13, 10, 1, 18, 25, 26, 2, 9, 6, 1, 14, 6, 7, 9, 9, 2, 1, 18, 1, 18, 2, 9, 2, 21, 9, 6, 5, 22, 11, 1, 2, 1, 18, 5, 10, 1, 2, 13, 42, 1, 18, 5, 1, 2
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OFFSET
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1,1
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EXAMPLE
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A001597(5) = 16. Among 16+0 = 16, 16+1 = 17, 16+2 = 18 = 2*3*3, 16+3 = 19, 16+4 = 20 = 2*2*5, 16+5 = 21 = 3*7 there is no even semiprime, but 16+6 = 22 = 2*11 is an even semiprime. Hence a(5) = 6.
A001597(14) = 121. 121+0 = 121 = 11*11 is not even, but 121+1 = 122 = 2*61 is an even semiprime. Hence a(14) = 1.
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PROGRAM
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(MAGMA) PP:=[1] cat [ n: n in [2..5184] | IsPower(n) ]; [ k: p in PP | exists(k) {x: x in [0..100000] | IsEven(p+x) and IsPrime((p+x) div 2) } ]; /* Klaus Brockhaus, Apr 09 2007 */
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CROSSREFS
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Cf. A001597 (perfect powers).
Adjacent sequences: A127910 A127911 A127912 this_sequence A127914 A127915 A127916
Sequence in context: A089595 A034389 A084196 this_sequence A135991 A102003 A004587
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KEYWORD
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easy,nonn
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AUTHOR
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Giovanni Teofilatto (g.teofilatto(AT)tiscalinet.it), Apr 06 2007
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EXTENSIONS
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Edited, corrected and extended by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Apr 09 2007
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