cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A069715 GCD of digits of n is 1.

Original entry on oeis.org

1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 23, 25, 27, 29, 31, 32, 34, 35, 37, 38, 41, 43, 45, 47, 49, 51, 52, 53, 54, 56, 57, 58, 59, 61, 65, 67, 71, 72, 73, 74, 75, 76, 78, 79, 81, 83, 85, 87, 89, 91, 92, 94, 95, 97, 98, 100, 101, 102, 103, 104, 105, 106, 107, 108
Offset: 1

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Author

Labos Elemer, Apr 02 2002

Keywords

Examples

			All numbers with at least one digit equal to 1 are here.
		

Crossrefs

Cf. A011531 (subsequence), A240913 (subsequence).

Programs

  • Haskell
    a069715 n = a069715_list !! (n-1)
    a069715_list = filter ((== 1) . a052423) [1..]
    -- Reinhard Zumkeller, Apr 14 2014
    
  • Mathematica
    Do[s=Apply[GCD, IntegerDigits[n]]; If[Equal[s, 1], Print[n]], {n, 1, 256}]
  • PARI
    is(n)=gcd(digits(n))==1 \\ Charles R Greathouse IV, Nov 01 2014

Formula

A052423(a(n)) = 1. - Reinhard Zumkeller, Apr 14 2014
a(n) ~ n. In fact a(n) = n + O(n^(log 5/log 10)). - Charles R Greathouse IV, Nov 01 2014