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 A004151 Omit trailing zeros from n. 20
 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 11, 12, 13, 14, 15, 16, 17, 18, 19, 2, 21, 22, 23, 24, 25, 26, 27, 28, 29, 3, 31, 32, 33, 34, 35, 36, 37, 38, 39, 4, 41, 42, 43, 44, 45, 46, 47, 48, 49, 5, 51, 52, 53, 54, 55, 56, 57, 58, 59, 6, 61, 62, 63, 64, 65, 66, 67, 68, 69, 7, 71, 72, 73, 74, 75, 76, 77, 78, 79, 8, 81, 82, 83, 84, 85, 86, 87, 88, 89, 9, 91, 92, 93, 94, 95, 96, 97, 98, 99, 1, 101, 102, 103, 104, 105, 106, 107, 108, 109, 11, 111, 112, 113, 114, 115, 116, 117, 118, 119, 12 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 FORMULA a(n) = a(n/10) if n mod 10 = 0, otherwise n. - Reinhard Zumkeller, Feb 02 2012 G.f. A(x) satisfies: A(x) = A(x^10) + x/(1 - x)^2 - 10*x^10/(1 - x^10)^2. - Ilya Gutkovskiy, Oct 27 2019 Sum_{k=1..n} a(k) ~ (5/11) * n^2. - Amiram Eldar, Nov 20 2022 MATHEMATICA Flatten[Table[n/Take[Intersection[Divisors[n], 10^Range[0, Floor[Log[10, n]]]], -1], {n, 120}]] (* Alonso del Arte, Feb 02 2012 *) Table[n/10^IntegerExponent[n, 10], {n, 120}] (* Harvey P. Dale, May 02 2018 *) PROG (Haskell) a004151 = until ((> 0) . (`mod` 10)) (`div` 10) -- Reinhard Zumkeller, Feb 01 2012 (PARI) a(n)=n/10^valuation(n, 10) \\ Charles R Greathouse IV, Oct 31 2012 (Python) def A004151(n): a, b = divmod(n, 10) while not b: n = a a, b = divmod(n, 10) return n # Chai Wah Wu, Feb 20 2024 CROSSREFS Cf. A004719, A122840. Sequence in context: A068636 A328131 A004719 * A151765 A343750 A107603 Adjacent sequences: A004148 A004149 A004150 * A004152 A004153 A004154 KEYWORD nonn,base,easy AUTHOR N. J. A. Sloane STATUS approved

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Last modified September 17 11:42 EDT 2024. Contains 375987 sequences. (Running on oeis4.)