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A341717
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a(n) = smallest m >= n such that the decimal concatenation n||n+1||n+2||...||m is prime, or -1 if no such prime exists.
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10
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OFFSET
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2,1
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COMMENTS
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These are the values of n+k from A341715. See that entry for more information.
See A084559 (the same for nonprime indices) for further information. - M. F. Hasler, Feb 22 2021
Suppose n > 3. If n == 2 (mod 3), then a(n) == 3 or 5 (mod 6). If n = 0 or 1 (mod 3), then a(n) == 1 (mod 6) (see A341716). - Chai Wah Wu, Feb 22 2021
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LINKS
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FORMULA
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MATHEMATICA
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Array[Block[{k = #, s = #}, While[! PrimeQ[s], k++; s = FromDigits[IntegerDigits[s]~Join~IntegerDigits[k]]]; k] &, 8, 2] (* Michael De Vlieger, Feb 22 2021 *)
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PROG
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CROSSREFS
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KEYWORD
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nonn,base,more
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AUTHOR
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STATUS
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approved
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