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 A054684 Numbers whose sum of digits is odd. 13
 1, 3, 5, 7, 9, 10, 12, 14, 16, 18, 21, 23, 25, 27, 29, 30, 32, 34, 36, 38, 41, 43, 45, 47, 49, 50, 52, 54, 56, 58, 61, 63, 65, 67, 69, 70, 72, 74, 76, 78, 81, 83, 85, 87, 89, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 111, 113, 115, 117, 119, 120, 122, 124, 126, 128, 131 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Union of A179083 and A179085; A179081(a(n)) = 1. - Reinhard Zumkeller, Jun 28 2010 Equivalently, integers with an odd number of odd digits. - Bernard Schott, Nov 06 2022 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..1000 FORMULA a(n) = n * 2 - 1 for the first 5 numbers; a(n) = n * 2 for the second 5 numbers. From Robert Israel, Jun 27 2017: (Start) a(n) = 2*n-2 if floor((n-1)/5) is in the sequence, 2*n-1 if not. G.f. g(x) satisfies g(x) = (1-x)*(1+x+x^2+x^3+x^4)^2*g(x^10)/x^9 + x^2*(2+x^4+3*x^5-x^9+3*x^10)/((1-x)*(1+x^5))^2. (End) EXAMPLE 1, 3, 5, 7, 9, 10(1), 12(3), 14(5), 16(7), 18(9), 21(3) and so on. MAPLE [seq(`if`(convert(convert(2*n-1, base, 10), `+`)::odd, 2*n-1, 2*n-2), n=1..501)]; MATHEMATICA Select[Range[200], OddQ[Total[IntegerDigits[#]]]&] (* Harvey P. Dale, Nov 27 2021 *) PROG (PARI) is(n)=my(d=digits(n)); sum(i=1, #d, d[i])%2 \\ Charles R Greathouse IV, Aug 09 2013 (PARI) isok(m) = sumdigits(m) % 2; \\ Michel Marcus, Nov 06 2022 (PARI) a(n) = n=2*(n-1); n + !(sumdigits(n)%2); \\ Kevin Ryde, Nov 07 2022 (Python) def ok(n): return sum(map(int, str(n)))&1 print([k for k in range(132) if ok(k)]) # Michael S. Branicky, Nov 06 2022 CROSSREFS Cf. A054683, A137233 (number of n-digits terms). Cf. A356929 (even number of even digits). A294601 (exactly one odd decimal digit) is a subsequence. Sequence in context: A287774 A308412 A327254 * A294601 A358529 A080207 Adjacent sequences:  A054681 A054682 A054683 * A054685 A054686 A054687 KEYWORD nonn,easy,base AUTHOR Odimar Fabeny, Apr 19 2000 EXTENSIONS More terms from James A. Sellers, Apr 19 2000 STATUS approved

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Last modified November 26 04:03 EST 2022. Contains 358353 sequences. (Running on oeis4.)