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Search: id:A111101
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| 1, 2, 3, 7, 8, 12, 13, 3138, 3142, 3146, 3147, 6272, 6273, 6277, 6278, 11112006825564294, 11112006825564295, 11112006825567420, 11112006825567421, 11112006825570546, 11112006825570550
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OFFSET
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1,2
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COMMENT
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a(n) is prime for n = 2, 3, 4, 7, 14. a(n) is semiprime for n = 9, 11, 18, 26.
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FORMULA
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a(n) = Sum[from i to n] A000001(i)^A000001(i).
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EXAMPLE
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a(7) = 1^1 + 1^1 + 1^1 + 2^2 + 1^1 + 2^2 + 1^1 = 13, which is prime.
a(14) = 1^1 + 1^1 + 1^1 + 2^2 +1^1 + 2^2 + 1^1 + 5^5 + 2^2 + 2^2+ 1^1 + 5^5 + 1^1 + 2^2 = 6277, which is prime.
a(29) = 1^1 + 1^1 + 1^1 + 2^2 + 1^1 + 2^2 + 1^1 + 5^5 + 2^2 + 2^2+ 1^1 + 5^5 + 1^1 + 2^2 + 1^1 + 14^14 + 1^1 + 5^5 + 1^1 + 5^5 + 2^2 + 2^2 + 1^1 + 15^15 + 2^2 + 2^2 + 5^5 + 4^4 + 1^1 = 449005897206433320.
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CROSSREFS
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Cf. A000001.
Sequence in context: A055053 A047221 A032967 this_sequence A003307 A105601 A033082
Adjacent sequences: A111098 A111099 A111100 this_sequence A111102 A111103 A111104
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post (jvospost3(AT)gmail.com), Oct 13 2005
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