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A116173
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Numbers k such that k concatenated with k+2 gives the product of two numbers which differ by 6.
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9
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OFFSET
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1,1
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COMMENTS
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Also numbers k such that k concatenated with k+7 gives the product of two numbers which differ by 4.
If k+2 and k-5 have the same number of digits, the k is also in A116126, because k//k+2 = 10^d*k + k + 2 = m*(m+6) then implies a representation k//k-5 = 10^d*k + k - 5 = m*(m+6)-7 = (m-1)*(m+7). - R. J. Mathar, Aug 10 2008
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LINKS
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Table of n, a(n) for n=1..4.
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EXAMPLE
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6752089//6752091 = 8217107 * 8217113, where // denotes concatenation.
6752089//6752096 = 8217108 * 8217112.
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CROSSREFS
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Cf. A116159, A116172, A116174, A116187, A116304.
Cf. A115430, A116205, A116207, A116187, A116337.
Sequence in context: A309385 A022237 A273753 * A345608 A346282 A088238
Adjacent sequences: A116170 A116171 A116172 * A116174 A116175 A116176
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KEYWORD
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nonn,base
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AUTHOR
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Giovanni Resta, Feb 06 2006
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EXTENSIONS
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Edited by N. J. A. Sloane, Apr 12 2007
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STATUS
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approved
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