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Search: id:A071240
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| A071240 |
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Arithmetic mean of k and R(k) where k is a number using all odd digits and R(k) is its digit reversal (A004086). |
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3
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| 1, 3, 5, 7, 9, 11, 22, 33, 44, 55, 22, 33, 44, 55, 66, 33, 44, 55, 66, 77, 44, 55, 66, 77, 88, 55, 66, 77, 88, 99, 111, 212, 313, 414, 515, 131, 232, 333, 434, 535, 151, 252, 353, 454, 555, 171, 272, 373, 474, 575, 191, 292, 393, 494, 595, 212, 313, 414, 515, 616
(list; graph; listen)
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OFFSET
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0,2
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FORMULA
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{ k + R(k)}/2 where k uses only odd digits 1, 3, 5, 7 and 9.
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MAPLE
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reversal := proc(n) local i, len, new, temp: new := 0: temp := n: len := floor(log[10](n+.1))+1: for i from 1 to len do new := new+irem(temp, 10)*10^(len-i): temp := floor(temp/10): od: RETURN(new): end: allodd := proc(n) local i, flag, len, temp: temp := n: flag := 1: if n=0 then flag := 0 fi: len := floor(log[10](n+.1))+1: for i from 1 to len do if irem(temp, 10) mod 2 = 1 then temp := floor(temp/10) else flag := 0 fi: od: RETURN(flag): end: for n from 1 to 501 by 2 do if allodd(n) = 1 then printf(`%d, `, (n+reversal(n))/2) fi: od:
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CROSSREFS
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Cf. A071241, A071242.
Sequence in context: A039578 A033032 A103148 this_sequence A088049 A029660 A004156
Adjacent sequences: A071237 A071238 A071239 this_sequence A071241 A071242 A071243
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KEYWORD
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base,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), May 20 2002
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EXTENSIONS
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More terms and Maple code from James A. Sellers (sellersj(AT)math.psu.edu), May 28, 2002
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