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Search: id:A093781
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| A093781 |
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a(n) is the position of the prime 5 in the Euclid-Mullin (EM) sequence of type A000945, if it was started with prime(n) instead of 2. |
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2
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| 7, 7, 1, 7, 18, 10, 3, 4, 11, 7, 8, 8, 10, 7, 3, 13, 8, 6, 7, 8, 6, 4, 7, 8, 9, 4, 6, 3, 4, 11, 5, 8, 3, 4, 4, 8, 8, 13, 3, 10, 21, 15, 6, 8, 3, 4, 13, 5, 3, 4, 8, 14, 6, 10, 3, 6, 12, 6, 10, 6, 6, 13, 8, 4, 6, 3, 11, 5, 3, 4, 13, 6, 10, 8, 4, 26, 8, 7, 11, 4, 7, 10, 7, 5, 4, 7, 16, 8, 7, 9, 3, 5, 5, 6
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OFFSET
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1,1
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COMMENT
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a(38) = 13 because prime(38) = 163, and the corresponding EM sequence is {163,2,3,11,7,75307,3931,5399,3041,409,179,92958641873,5,2003,...}, where 5 appears at the 13th position. - David Wasserman (dwasserm(AT)earthlink.net), Apr 19 2007
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LINKS
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David Wasserman (dwasserm(AT)earthlink.net), Apr 19 2007, Table of n, a(n) for n = 1..1000
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PROGRAM
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(PARI) em(i) = local(p, c, n, f, q); p = prime(i); if (p == 5, return(1)); c = 1; n = p; while (1, c++; f = factor(n + 1, 2^31 - 1); q = f[1, 1]; if (!isprime(q), f = factor(n + 1); q = f[1, 1]); if (q == 5, return(c)); n *= q); - David Wasserman (dwasserm(AT)earthlink.net), Apr 19 2007
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CROSSREFS
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Cf. A000945, A051308-A051334, A056756, A093777-A093780.
Cf. A093782.
Sequence in context: A140136 A011376 A011452 this_sequence A108390 A102400 A113810
Adjacent sequences: A093778 A093779 A093780 this_sequence A093782 A093783 A093784
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), May 04 2004
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EXTENSIONS
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More terms from David Wasserman (dwasserm(AT)earthlink.net), Apr 19 2007
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