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.

Showing 1-3 of 3 results.

A101594 Numbers with exactly two distinct decimal digits, neither of which is 0.

Original entry on oeis.org

12, 13, 14, 15, 16, 17, 18, 19, 21, 23, 24, 25, 26, 27, 28, 29, 31, 32, 34, 35, 36, 37, 38, 39, 41, 42, 43, 45, 46, 47, 48, 49, 51, 52, 53, 54, 56, 57, 58, 59, 61, 62, 63, 64, 65, 67, 68, 69, 71, 72, 73, 74, 75, 76, 78, 79, 81, 82, 83, 84, 85, 86, 87, 89, 91, 92, 93, 94, 95, 96, 97, 98, 112, 113, 114, 115, 116, 117, 118, 119, 121, 122, 131
Offset: 1

Views

Author

David Wasserman, Dec 07 2004

Keywords

Comments

First differs from A125290 at a(83) = 131 != 123 = A101594(83). - Michael S. Branicky, Dec 13 2021

Crossrefs

Programs

  • Haskell
    a101594 n = a101594_list !! (n-1)
    a101594_list = filter ((== 2) . a043537) a052382_list
    -- Reinhard Zumkeller, Jun 18 2013
    
  • Mathematica
    Select[Range[200], FreeQ[#, 0] && Length[Union[#]] == 2 & [IntegerDigits[#]] &] (* Paolo Xausa, May 06 2024 *)
  • Python
    def ok(n): s = set(str(n)); return len(s) == 2 and "0" not in s
    print([k for k in range(132) if ok(k)]) # Michael S. Branicky, Dec 13 2021

Formula

A168046(a(n)) * A043537(A004719(a(n))) = 2. - Reinhard Zumkeller, Jun 18 2013

A083984 If k is a number with exactly two distinct decimal digits, say a and b, neither of which is 0 (i.e., a member of A101594), define the self-complement of k, SC(k), to be the number obtained by replacing a with b and vice versa. E.g. SC(232233) = 323322. Sequence contains numbers n such that n and SC(n) are relatively prime.

Original entry on oeis.org

13, 14, 16, 17, 19, 23, 25, 29, 31, 32, 34, 35, 37, 38, 41, 43, 47, 49, 52, 53, 56, 58, 59, 61, 65, 67, 71, 73, 74, 76, 79, 83, 85, 89, 91, 92, 94, 95, 97, 98, 112, 113, 115, 116, 118, 119, 121, 122, 131, 133, 151, 155, 166, 181, 188, 191, 199, 211, 212, 221, 223, 227
Offset: 1

Views

Author

Amarnath Murthy, May 22 2003

Keywords

Examples

			25 is a member as 25 and 52 are relatively prime, but 24 is not a member as 24 and 42 are not coprime.
		

Crossrefs

Extensions

More terms from David Wasserman, Dec 07 2004
Offset corrected by Andrew Howroyd, Sep 29 2024

A083986 If k is a number with exactly two distinct decimal digits, say a and b, neither of which is 0 (i.e., a member of A101594), define the self-complement of k, SC(k), to be the number obtained by replacing a with b and vice versa. Then a(n) = lcm(A101594(n), SC(A101594(n))).

Original entry on oeis.org

84, 403, 574, 255, 976, 1207, 162, 1729, 84, 736, 168, 1300, 806, 216, 1148, 2668, 403, 736, 1462, 1855, 252, 2701, 3154, 1209, 574, 168, 1462, 270, 1472, 3478, 336, 4606, 255, 1300, 1855, 270, 3640, 1425, 4930, 5605, 976, 806, 252, 1472, 3640, 5092, 2924
Offset: 1

Views

Author

Amarnath Murthy, May 22 2003

Keywords

Examples

			a(7) = lcm(18, 81) = 162.
		

Crossrefs

Extensions

Corrected and extended by David Wasserman, Dec 07 2004
Offset corrected by Andrew Howroyd, Sep 29 2024
Showing 1-3 of 3 results.