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A062886
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Smallest multiple of 2n+1 with property that digits are odd and each digit is two more (mod 10) than the previous digit; or 0 if no such number exists.
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1
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1, 3, 5, 7, 9, 913, 13, 135, 357, 57, 357, 1357, 0, 135, 9135, 91357, 9135791357913, 35, 13579, 13579135791, 7913, 3579135791357913, 135, 913579135791, 79135, 357, 1357913, 7913579135, 57, 1357, 7913579135791357913579, 9135, 791357913579135791357913579135
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OFFSET
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0,2
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COMMENTS
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The size of terms of this sequence varies wildly. For example, a(453) has 755 digits, while a(456)=913. The only numbers n for which a(n)=0 up to n=500 are those for which 2*n+1 is divisible by 25. - Nathaniel Johnston, May 19 2011
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LINKS
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EXAMPLE
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a(7) = 135 = 3*(2*7 + 1) has increasing odd digits.
a(12) does not exist because a number in base 10 divisible by 25 ends with 00, 25, 50 or 75, so a(12)=0.
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MAPLE
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A062886 := proc(n) local d, j, k, p, val: p:=2*n+1: if(p mod 25 = 0)then return 0: fi: for j from 1 do for d from 1 to 9 by 2 do val:=0: for k from 1 to j do val:=val+10^(j-k)*((d+2*(k-1)) mod 10): od: if(val mod p = 0)then return val: fi: od: od: end: seq(A062886(n), n=0..30); # Nathaniel Johnston, May 19 2011
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CROSSREFS
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KEYWORD
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nonn,base
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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