A225985 List the positive numbers, remove even digits (including zeros) from each term; sequence = remaining terms.

1, 3, 5, 7, 9, 1, 11, 1, 13, 1, 15, 1, 17, 1, 19, 1, 3, 5, 7, 9, 3, 31, 3, 33, 3, 35, 3, 37, 3, 39, 1, 3, 5, 7, 9, 5, 51, 5, 53, 5, 55, 5, 57, 5, 59, 1, 3, 5, 7, 9, 7, 71, 7, 73, 7, 75, 7, 77, 7, 79, 1, 3, 5, 7, 9, 9, 91, 9, 93, 9, 95, 9, 97, 9, 99, 1, 11, 1, 13

Offset

1,2

Links

Paul Tek, Table of n, a(n) for n = 1..10000

Formula

a(A226091(n)) = A014261(n). - Reinhard Zumkeller, May 26 2013

Example

The natural numbers with at least one odd digit in their decimal representation are: 1, 3, 5, 7, 9, 10, 11, 12, 13, ...
By excluding their even digits, we obtain: 1, 3, 5, 7, 9, 1, 11, 1, 13, ...
Hence: a(1)=1, a(2)=3, a(3)=5, a(4)=7, a(5)=9, a(6)=1, a(7)=11, a(8)=1, a(9)=13, .... [Example corrected by Paul Tek, May 24 2013]

Mathematica

FromDigits[DeleteCases[IntegerDigits[#], _?EvenQ]]&/@Range[200]/. (0-> Nothing) (* Harvey P. Dale, Apr 04 2017 *)

Prog

(Haskell)
a225985 n = a225985_list !! (n-1)
a225985_list = map read $ filter (not . null) $
    map (filter (`elem` "13579") . show) [0..] :: [Integer]
-- Reinhard Zumkeller, May 26 2013
(Python)
from itertools import count, islice
def agen(): # generator of terms
    for n in count(1):
        removed  = "".join(d if d in "13579" else "" for d in str(n))
        if removed != "": yield int(removed)
print(list(islice(agen(), 80))) # Michael S. Branicky, Aug 05 2022

Crossrefs

Cf. A038573.

Cf. A014261 (duplicates removed), A226091.

Sequence in context: A316988 A031312 A141518 * A032764 A131669 A004155

Adjacent sequences: A225982 A225983 A225984 * A225986 A225987 A225988

Keyword

nonn,base,look

Author

Dave Durgin, May 22 2013

Extensions

Definition clarified by N. J. A. Sloane, Aug 06 2022 at the suggestion of Michel Marcus

Status

approved