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 A173639 Numbers n such that the sum of the digits of 11*n is odd. 1
 19, 28, 29, 37, 38, 39, 46, 47, 48, 49, 55, 56, 57, 58, 59, 64, 65, 66, 67, 68, 69, 73, 74, 75, 76, 77, 78, 79, 82, 83, 84, 85, 86, 87, 88, 89, 119, 128, 129, 137, 138, 139, 146, 147, 148, 149 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Note that the first 18 multiples of 11 have even digital sums. Indices of odd entries in A136614. - R. J. Mathar, Nov 23 2010 a(n) = A075517(n+9) = A248013(n+10) for n <= 36. - Giovanni Resta, Sep 04 2017 LINKS Harvey P. Dale, Table of n, a(n) for n = 1..1000 EXAMPLE 19 is on the list because 11*19 = 209 and 2+0+9 is odd. MAPLE L := []; for n to 150 do if `mod`(add(i, i = convert(11*n, base, 10)), 2) = 1 then L := [op(L), n] end if end do; L; MATHEMATICA Select[Range[200], OddQ[Total[IntegerDigits[11#]]]&] (* Harvey P. Dale, May 28 2012 *) PROG (Python) ans = [] for n in range(1, 151):     N, s = 11*n, 0     while N:         s += N % 10         N //= 10     if s % 2:         ans.append(n) print(ans) (Haskell) a173639 n = a173639_list !! (n-1) a173639_list = filter (odd . a007953 . (* 11)) [0..] -- Reinhard Zumkeller, Jul 05 2014 CROSSREFS Cf. A008593, A007953. Sequence in context: A304367 A298638 A291884 * A091448 A067777 A065207 Adjacent sequences:  A173636 A173637 A173638 * A173640 A173641 A173642 KEYWORD nonn,base AUTHOR David Radcliffe, Nov 23 2010 STATUS approved

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Last modified September 23 12:06 EDT 2021. Contains 347616 sequences. (Running on oeis4.)