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A052192
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Smallest a(n) for which n*a(n) has no isolated digits.
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2
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11, 11, 11, 11, 11, 11, 11, 11, 11, 110, 1, 37, 88, 242, 37, 143, 66, 37, 121, 55, 37, 1, 99, 37, 44, 44, 37, 121, 77, 110, 143, 209, 1, 33, 33, 33, 3, 88, 143, 55, 55, 132, 77, 1, 99, 121, 165, 706, 678, 22, 22, 22, 22, 22, 1, 99, 1169, 77, 132, 55, 55, 143, 88, 121
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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a(23)=99 since 23*99=2277 and all the digits of 2277 have a neighboring digit which is the same.
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MATHEMATICA
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isol[n_ ] := Module[{}, L={11}~Join~IntegerDigits[n ]~Join~{11}; l=Length[L ]; Apply[And, Table[L[[i ] ]==L[[i-1 ] ]||L[[i ] ]==L[[i+1 ] ], {i, 2, l-1} ] ] ] a[n_ ] := a[n ]=Module[{}, m=0; While[Not[isol[m ] ], m=m+n ]; m ] Table[a[i ], {i, 1, 100} ]/Range[100 ]
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PROG
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(Haskell)
import Data.List (group, findIndex)
import Data.Maybe (fromJust)
a052192 n = fromJust $
findIndex ((> 1) . minimum . map length . group . show) $ [0, n..]
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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