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 A217682 Record bases for first finding prime by concatenation of numbers decremented from terms of A217681. 1
 2, 3, 8, 9, 10, 13, 14, 18, 21 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The partner sequence gives a monotone sequence of numbers that require increasing values of a base of arithmetic before any prime can be found by concatenating numbers decremented in sequence through 1. This sequence gives the record base required by each. LINKS Table of n, a(n) for n=1..9. EXAMPLE When numbers are concatenated in decreasing sequence in binary from each number 2-9 (10 to 1001 in binary), inevitably there is a prime in the sequence: 101 is prime in binary, as is 11101, etc. But this is not the case for 10 (binary 1010). The number represented as 1011002221201211 in base 3, the concatenation of the decimal values 10 down to 4, is a prime (16532797 in decimal). So the record base is 3 for the 2nd entry here. CROSSREFS Cf. A217681. Sequence in context: A277971 A080288 A278560 * A169868 A363088 A191159 Adjacent sequences: A217679 A217680 A217681 * A217683 A217684 A217685 KEYWORD nonn,base,less,more AUTHOR James G. Merickel, Oct 10 2012 EXTENSIONS a(9) added by James G. Merickel, May 05 2013 STATUS approved

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Last modified June 25 13:13 EDT 2024. Contains 373705 sequences. (Running on oeis4.)