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A109204
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Minimal value of k>0 such that n^9 + k^2 is a semiprime.
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2
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2, 3, 5, 10, 5, 2, 11, 4, 7, 2, 9, 4, 7, 5, 3, 22, 7, 16, 7, 2, 39, 2, 25, 12, 5, 7, 21, 2, 5, 3, 7, 16, 9, 17, 5, 24, 19, 4, 3, 20, 7, 6, 11, 4, 3, 4, 17, 12, 17, 2, 7, 70, 3, 3, 5, 2, 11, 16, 5, 42, 7, 4, 3, 26, 3, 9, 25, 26, 9, 5, 33, 6, 23, 12, 23, 2, 9, 6, 7, 2, 23, 4, 3, 16, 11, 16, 9, 2, 3
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OFFSET
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0,1
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LINKS
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Table of n, a(n) for n=0..88.
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EXAMPLE
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a(0) = 2 because 0^9 + 1^2 = 1 is not semiprime, but 0^9 + 2^2 = 4 = 2^2 is.
a(1) = 3 because 1^9 + 1^2 and 1^9 + 2^2 are not semiprime, but 1^9 + 3^2 = 10 = 2 * 5 is semiprime.
a(2) = 5 because 2^9 + 5^2 = 537 = 3 * 179 is semiprime, but 2^9 plus no smaller square is.
a(51) = 70 because 51^9 + 70^2 = 2334165173095351 = 43063 * 54203496577 and for no smaller k>0 is 51^9 + k^2 a semiprime.
a(100) = 7 because 100^9 + 7^2 = 1000000000000000049 = 157 * 6369426751592357 and for no smaller k>0 is 100^9 + k^2 a semiprime.
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CROSSREFS
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Cf. A001358, A108714, A109197, A109198, A109199, A109200, A109201, A109202, A109203.
Sequence in context: A179332 A081938 A129500 * A038807 A094542 A175481
Adjacent sequences: A109201 A109202 A109203 * A109205 A109206 A109207
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KEYWORD
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easy,nonn
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AUTHOR
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Jonathan Vos Post, Jul 04 2005
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STATUS
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approved
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