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A014261
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Numbers that contain odd digits only.
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15
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1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 31, 33, 35, 37, 39, 51, 53, 55, 57, 59, 71, 73, 75, 77, 79, 91, 93, 95, 97, 99, 111, 113, 115, 117, 119, 131, 133, 135, 137, 139, 151, 153, 155, 157, 159, 171, 173, 175, 177, 179, 191, 193, 195, 197, 199, 311, 313, 315, 317, 319
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Or, numbers whose product of digits is odd.
A121759(a(n)) = a(n); A000035(A007959(a(n))) = 1. - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Nov 30 2007
a(n+1) - a(n) = A164898(n). [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 30 2009]
Complement of A007928; A196563(a(n)) = 0. [Reinhard Zumkeller, Oct 04 2011]
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LINKS
| R. Zumkeller, Table of n, a(n) for n = 1..10000 [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 30 2009]
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FORMULA
| Contribution from Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 30 2009: (Start)
a(n+1) = h(a(n)) with h(x) = 1 + (if x mod 10 < 9 then x + x mod 2 else 10*h(floor(x/10)));
a(n) = f(n, 1) where f(n, x) = if n=1 then x else f(n-1, h(x)). (End)
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MATHEMATICA
| f[n_Integer] := Block[{d = IntegerDigits[n], c = 0, l}, l = Length[d] - 1; If[ OddQ[ d[[ -1]]], d[[ -1]]++ ]; d[[ -1]]++; If[ d[[ -1]] > 10, c++; d[[ -1]] = 1]; While[l != 0, If[c == 1, d[[l]]++; c-- ]; If[ EvenQ[ d[[l]]], d[[l]]++ ]; If[ d[[l]] > 10, c++; d[[l]] = 1]; l-- ]; If[c == 1, d[[1]] = d[[1]] + 10]; FromDigits[d]]; NestList[f, 1, 50]
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PROG
| (MAGMA) [ n : n in [1..129] | IsOdd(&*Intseq(n, 10)) ];
(Haskell)
a014261 n = a014261_list !! (n-1)
a014261_list = filter (all (`elem` "13579") . show) [1, 3..]
-- Reinhard Zumkeller, Jul 05 2011
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CROSSREFS
| Similar to but different from A066640.
A005408, A010879. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Aug 30 2009]
Cf. A014263; subsequence of A059708.
Sequence in context: A138217 A074775 A143451 * A066640 A137507 A061808
Adjacent sequences: A014258 A014259 A014260 * A014262 A014263 A014264
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KEYWORD
| nonn,base,easy
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
| More terms from rgwv, Oct 18 2002
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