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A078274
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a(n) is the number from which if odd-positioned digits are deleted then one gets the concatenation of first n odd numbers, while if even-positioned digits are deleted then one gets reverse concatenation of first n odd numbers. Position of least significant digit is considered to be 1.
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3
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11, 1331, 153351, 17355371, 1937557391, 11315977951311, 133151719917151331, 1531537191111917351351, 17315571931111113917551371, 193157719511131131115917751391, 1132597197111511331151117917952311, 13325172991117113511531171119927152331
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OFFSET
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1,1
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LINKS
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EXAMPLE
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a(4) = 17355371: deleting alternate digits starting from the LSD gives 1357. Deleting the other digits gives 7531.
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MATHEMATICA
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rif[n_]:=Module[{idn=Flatten[IntegerDigits/@Range[1, 2n-1, 2]]}, FromDigits[ Riffle[idn, Reverse[idn]]]]; Array[rif, 15] (* Harvey P. Dale, Apr 11 2012 *)
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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EXTENSIONS
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More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 19 2003
Corrected and extended by Harvey P. Dale, Apr 11 2012
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STATUS
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approved
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