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.

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A187389 a(n) = floor(r*n), where r = 1 + sqrt(7) + sqrt(6); complement of A187390.

Original entry on oeis.org

6, 12, 18, 24, 30, 36, 42, 48, 54, 60, 67, 73, 79, 85, 91, 97, 103, 109, 115, 121, 128, 134, 140, 146, 152, 158, 164, 170, 176, 182, 188, 195, 201, 207, 213, 219, 225, 231, 237, 243, 249, 256, 262, 268, 274, 280, 286, 292, 298, 304, 310, 316, 323, 329, 335, 341, 347, 353, 359, 365, 371, 377, 384, 390, 396, 402, 408, 414, 420, 426
Offset: 1

Views

Author

Clark Kimberling, Mar 09 2011

Keywords

Comments

A187389 and A187390 are the Beatty sequences based on r=1+sqrt(7)+sqrt(6) and s=1+sqrt(7)-sqrt(6); 1/r+1/s=1.

Crossrefs

Cf. A187390.

Programs

  • Mathematica
    k=7; r=1+k^(1/2)+(k-1)^(1/2); s=1+k^(1/2)-(k-1)^(1/2);
Table[Floor[r*n],{n,1,80}]  (* A187389 *)
Table[Floor[s*n],{n,1,80}]  (* A187390 *)

Formula

a(n)=floor(r*n), where r=1+sqrt(7)+sqrt(6).

A248910 Numbers with no zeros in base-6 representation.

Original entry on oeis.org

1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 31, 32, 33, 34, 35, 43, 44, 45, 46, 47, 49, 50, 51, 52, 53, 55, 56, 57, 58, 59, 61, 62, 63, 64, 65, 67, 68, 69, 70, 71, 79, 80, 81, 82, 83, 85, 86, 87, 88, 89, 91, 92
Offset: 1

Views

Author

Reinhard Zumkeller, Mar 08 2015

Keywords

Comments

Different from A039215, A047253, A184522, A187390, A194386.

Links

Crossrefs

Cf. A007092, A100969 (subsequence).
Zeroless numbers in some other bases <= 10: A000042 (base 2), A032924 (base 3), A023705 (base 4), A255805 (base 8), A255808 (base 9), A052382 (base 10).

Programs

  • Haskell
    a248910 n = a248910_list !! (n-1)
a248910_list = iterate f 1 where
   f x = 1 + if r < 5 then x else 6 * f x'  where (x', r) = divMod x 6
  • Mathematica
    Select[Range[100], DigitCount[#,6, 0] == 0 &] (* Paolo Xausa, Jun 29 2025 *)
  • PARI
    isok(m) = vecmin(digits(m, 6)) > 0; \\ Michel Marcus, Jan 23 2022
  • Python
    from sympy import integer_log
def A248910(n):
    m = integer_log(k:=(n<<2)+1,5)[0]
    return sum((1+(k-5**m)//(5**j<<2)%5)*6**j for j in range(m)) # Chai Wah Wu, Jun 28 2025
Showing 1-2 of 2 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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