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A004151 Omit trailing zeros from n. 19
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
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
CROSSREFS
Sequence in context: A068636 A328131 A004719 * A151765 A343750 A107603
KEYWORD
nonn,base,easy
AUTHOR
STATUS
approved

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Last modified November 30 02:55 EST 2023. Contains 367452 sequences. (Running on oeis4.)