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A117190
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Integer k such that 10^n + k = A115062(n).
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1
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1, 1, 1, -3, 7, 3, 3, -9, 7, 7, 19, 3, -11, -29, -27, -11, 61, -3, 3, -39, -11, -101, 9, -23, 7, 13, 67, -99, -209, -27, -11, -27, -21, -9, 193, -23, 67, 43, -59, 3, -17, 109, 63, 57, 31, -9, -33, 33, -33, 9, -57, 121, -231, 171, 31, 21, 3, -93, -149, 19, 7, -39, -83, 121, -51, 49, 49, 49, 99, 9, 33, -53, 39, 79, -47, 129, 133
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OFFSET
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0,4
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COMMENTS
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For terms after the first several, 10^n + a(n) is only known to be a highly probable prime. If, for m>0, 10^n - m and 10^n + m are both nearest primes to 10^n, a(n) = -m. For example, a(17) = -3 as 10^17-3 and 10^17+3 are the nearest primes to 10^17. Similarly, a(45) = -9 with both 10^45-9 and 10^45+9 prime.
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LINKS
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FORMULA
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EXAMPLE
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a(4) = 7 as 10^4 + 7 = 10007 = A115062(4), the nearest prime to 10^4.
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MAPLE
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a:= n-> (t->((p, q)->`if`(q-t<t-p, q, p)-t)(`if`(t=1, -1,
prevprime(t)), nextprime(t)))(10^n):
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CROSSREFS
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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