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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A353114 Base-6 representation of A000422(n).

Original entry on oeis.org

1, 33, 1253, 32001, 1055253, 22005133, 432020401, 12410423013, 242000505413, 5014143322001, 2210214121042333, 1105325341502010053, 333110135101300035201, 144230053432212010304453, 51542110115212012113433133
Offset: 1

Views

Author

Seiichi Manyama, Apr 24 2022

Keywords

Crossrefs

Programs

  • Ruby
    def A(k, n)
      (1..n).map{|i| (1..i).to_a.reverse.join.to_i.to_s(k).to_i}
    end
    p A(6, 20)

Formula

a(n) = A007092(A000422(n)).

A004053 For m=2,3,..., write m in bases 2,3,..,m.

Original entry on oeis.org

10, 11, 10, 100, 11, 10, 101, 12, 11, 10, 110, 20, 12, 11, 10, 111, 21, 13, 12, 11, 10, 1000, 22, 20, 13, 12, 11, 10, 1001, 100, 21, 14, 13, 12, 11, 10, 1010, 101, 22, 20, 14, 13, 12, 11, 10, 1011, 102, 23, 21, 15, 14, 13, 12, 11, 10, 1100, 110, 30, 22, 20, 15, 14, 13, 12, 11, 10
Offset: 2

Views

Author

Johan Boye (johbo(AT)ida.liu.se)

Keywords

Examples

			Triangle begins:
    10;
    11,  10;
   100,  11, 10;
   101,  12, 11, 10;
   110,  20, 12, 11, 10;
   111,  21, 13, 12, 11, 10;
  1000,  22, 20, 13, 12, 11, 10;
  1001, 100, 21, 14, 13, 12, 11, 10;
  ...
		

Crossrefs

Programs

  • Mathematica
    FromDigits/@Flatten[Table[IntegerDigits[m,b],{m,2,20},{b,2,m}],1] (* Harvey P. Dale, Dec 01 2024 *)
  • PARI
    T(n, k) = fromdigits(digits(n, k), 10);
    tabl(nn) = for (n=2, nn, for (b=2, n, print1(T(n, b), ", "))); \\ Michel Marcus, Aug 30 2019

A004680 Primes written in base 6.

Original entry on oeis.org

2, 3, 5, 11, 15, 21, 25, 31, 35, 45, 51, 101, 105, 111, 115, 125, 135, 141, 151, 155, 201, 211, 215, 225, 241, 245, 251, 255, 301, 305, 331, 335, 345, 351, 405, 411, 421, 431, 435, 445, 455, 501, 515, 521, 525, 531, 551, 1011, 1015, 1021, 1025, 1035
Offset: 1

Views

Author

Keywords

Crossrefs

Analogs in other bases: A004676 (base 2), A001363 (base 3), A004678 (base 4), A004679 (base 5), A004681 (base 7), A004682 (base 8), A004683 (base 9), A000040 (base 10), A004684 (base 11).
Cf. A007092.

Programs

  • Magma
    [Seqint(Intseq(NthPrime(n),6)): n in [1..60]]; // G. C. Greubel, Oct 10 2018
  • Mathematica
    FromDigits/@IntegerDigits[Prime[Range[50]], 6] (* Vincenzo Librandi, Sep 03 2016 *)
  • PARI
    a(n)=subst(Pol(digits(prime(n),6)),'x,10) \\ Charles R Greathouse IV, Nov 06 2013
    
  • PARI
    vector(60, n, fromdigits(digits(prime(n), 6))) \\ G. C. Greubel, Oct 10 2018
    

Formula

a(n) = A007092(prime(n)). - Michel Marcus, Sep 03 2016

A037388 Numbers k such that every base-4 digit of k is a base-6 digit of k.

Original entry on oeis.org

1, 2, 3, 15, 38, 55, 63, 73, 85, 91, 117, 119, 121, 127, 170, 231, 236, 243, 255, 256, 257, 264, 276, 288, 289, 290, 291, 292, 293, 294, 306, 324, 325, 326, 327, 336, 341, 343, 348, 349, 350, 351, 362, 375, 381, 383, 408, 409, 410
Offset: 1

Views

Author

Keywords

Crossrefs

Programs

  • Haskell
    import Data.List ((\\), nub)
    a037388 n = a037388_list !! (n-1)
    a037388_list = filter f [1..] where
       f x = null $ nub (ds 4 x) \\ nub (ds 6 x)
       ds b x = if x > 0 then d : ds b x' else []  where (x', d) = divMod x b
    -- Reinhard Zumkeller, May 30 2013
  • Mathematica
    Select[Range[500],SubsetQ[IntegerDigits[#,6],IntegerDigits[#,4]]&] (* Harvey P. Dale, Mar 19 2018 *)

A037393 Numbers k such that every base-5 digit of k is a base-6 digit of k.

Original entry on oeis.org

1, 2, 3, 4, 6, 12, 18, 24, 31, 46, 56, 62, 75, 81, 87, 90, 91, 92, 93, 94, 99, 118, 124, 145, 150, 157, 226, 232, 243, 245, 291, 300, 306, 307, 308, 311, 312, 314, 322, 326, 332, 336, 337, 338, 341, 362, 372, 374, 378, 411, 416, 418
Offset: 1

Views

Author

Keywords

Crossrefs

Programs

  • Haskell
    import Data.List ((\\), nub)
    a037393 n = a037393_list !! (n-1)
    a037393_list = filter f [1..] where
       f x = null $ nub (ds 5 x) \\ nub (ds 6 x)
       ds b x = if x > 0 then d : ds b x' else []  where (x', d) = divMod x b
    -- Reinhard Zumkeller, May 30 2013

A057436 Contains digits 1 through 6 only.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 11, 12, 13, 14, 15, 16, 21, 22, 23, 24, 25, 26, 31, 32, 33, 34, 35, 36, 41, 42, 43, 44, 45, 46, 51, 52, 53, 54, 55, 56, 61, 62, 63, 64, 65, 66, 111, 112, 113, 114, 115, 116, 121, 122, 123, 124, 125, 126, 131, 132, 133, 134, 135, 136, 141, 142, 143
Offset: 1

Views

Author

Thomas Schulze (jazariel(AT)tiscalenet.it), Sep 08 2000

Keywords

Comments

Numbers whose digits can be generated by successively throwing a regular die with the numbers 1..6 and concatenating the results.

Examples

			The number 61 can be generated by throwing a die twice and combining the results, but 17 not.
		

Crossrefs

Programs

  • Haskell
    import Data.List (intersect)
    a057436 n = a057436_list !! (n-1)
    a057436_list = filter (null . (intersect "0789") . show) [1..]
    -- Reinhard Zumkeller, Mar 28 2012
    
  • Mathematica
    Select[Range[200],Max[IntegerDigits[#]]<=6&& DigitCount[#,10,0] ==0&]  (* Harvey P. Dale, Apr 04 2011 *)
    FromDigits/@Flatten[Table[Tuples[Range[6],n],{n,3}],1] (* Harvey P. Dale, Jul 26 2015 *)
  • Python
    from itertools import product
    A057436_list = [int(''.join(d)) for l in range(1,5) for d in product('123456',repeat=l)] # Chai Wah Wu, Sep 01 2021

Formula

a(n+1) = 1 + (if a(n) mod 10 < 6 then a(n) else a(a(n)\10)*10), a(0)=1. - Reinhard Zumkeller, Jul 13 2007

Extensions

Offset corrected by Reinhard Zumkeller, Aug 16 2011

A063432 Triangle read by rows in which k-th entry in row n is representation of n in base k, for 1 <= k <= n.

Original entry on oeis.org

1, 11, 10, 111, 11, 10, 1111, 100, 11, 10, 11111, 101, 12, 11, 10, 111111, 110, 20, 12, 11, 10, 1111111, 111, 21, 13, 12, 11, 10, 11111111, 1000, 22, 20, 13, 12, 11, 10, 111111111, 1001, 100, 21, 14, 13, 12, 11, 10, 1111111111, 1010, 101, 22, 20, 14, 13
Offset: 1

Views

Author

Henry Bottomley, Jul 20 2001

Keywords

Comments

Representation of n in base 1 is defined to be a concatenation of n 1's.
It is difficult to write twenty-one in base 11 using decimal digits.
Representation in bases greater than 10 are written in base 10. This is really nasty! - N. J. A. Sloane, Dec 06 2002

Examples

			Rows start (1), (11, 10), (111, 11, 10), (1111, 100, 11, 10), etc.
		

Crossrefs

Cf. A063431.
Columns are truncated versions of A000042, A007088, A007089, A007090, A007091, A007092, A007093, A007094, A007095, A000027 and perhaps A055649, etc.
Without the 1st column becomes A004053.

Programs

  • Mathematica
    f[n_] := Flatten[ Append[ {FromDigits[ Table[1, {n}]] }, Table[ FromDigits[ IntegerDigits[n, i]], {i, 2, n}]]]; Flatten[ Table[ f[n], {n, 1, 10}]] (* Robert G. Wilson v *)

A110604 Numbers n whose base 6 representations, interpreted as base 10 integers, are semiprimes.

Original entry on oeis.org

4, 6, 10, 11, 13, 14, 17, 21, 22, 23, 31, 35, 43, 47, 49, 50, 51, 57, 58, 61, 62, 63, 65, 71, 73, 74, 75, 77, 81, 82, 83, 85, 95, 105, 106, 109, 110, 111, 113, 118, 121, 123, 130, 131, 133, 143, 147, 151, 153, 155, 158, 173, 175, 177, 178, 181, 182, 185, 187, 190, 191
Offset: 1

Views

Author

Jonathan Vos Post, Jul 30 2005

Keywords

Comments

A108873 is the equivalent using base 3. A110602 is the equivalent using base 4. A110603 is the equivalent using base 5. A110605 is the equivalent using base 7. A110606 is the equivalent using base 8. A110607 is the equivalent using base 9.

Examples

			a(1) = 4 because 4 (base 6) = 4 and 4 (base 10) = 2 * 2, a semiprime (A001358).
a(2) = 6 because 6 (base 6) = 10 and 10 (base 10) = 2 * 5.
a(3) = 10 because 10 (base 6) = 14 and 14 (base 10) = 2 * 7.
a(4) = 11 because 11 (base 6) = 15 and 15 (base 10) = 3 * 5.
a(5) = 13 because 13 (base 6) = 21 and 21 (base 10) = 3 * 7.
		

Crossrefs

Programs

  • Mathematica
    Select[Range[191], Plus @@ Last /@ FactorInteger[FromDigits[IntegerDigits[ #, 6]]] == 2 &] (* Ray Chandler, Aug 05 2005 *)
    Select[Range[200],PrimeOmega[FromDigits[IntegerDigits[#,6]]]==2&] (* Harvey P. Dale, Oct 02 2011 *)

Extensions

Corrected and extended by Ray Chandler, Aug 05 2005

A353145 Decimal repunits written in base 6.

Original entry on oeis.org

0, 1, 15, 303, 5051, 123235, 2214223, 35452011, 1034052155, 15005255143, 302130544531, 5034313401115, 123013240420103, 2210234251121451, 35344212440150035, 1032151423443021023, 14535045221530334411, 301223205551110014555
Offset: 0

Views

Author

Seiichi Manyama, Apr 26 2022

Keywords

Crossrefs

Programs

  • PARI
    a(n) = fromdigits(digits((10^n-1)/9, 6));

Formula

a(n) = A007092(A002275(n)).

A037399 Numbers k such that every base-6 digit of k is a base-8 digit of k.

Original entry on oeis.org

1, 2, 3, 4, 5, 28, 80, 85, 86, 98, 115, 160, 172, 213, 266, 331, 345, 532, 691, 699, 705, 708, 717, 720, 727, 763, 765, 792, 799, 811, 819, 835, 851, 859, 861, 863, 864, 900, 916, 928, 1036, 1061, 1068, 1085, 1093, 1128, 1129, 1130
Offset: 1

Views

Author

Keywords

Crossrefs

Programs

  • Haskell
    import Data.List ((\\), nub)
    a037399 n = a037399_list !! (n-1)
    a037399_list = filter f [1..] where
       f x = null $ nub (ds 6 x) \\ nub (ds 8 x)
       ds b x = if x > 0 then d : ds b x' else []  where (x', d) = divMod x b
    -- Reinhard Zumkeller, May 30 2013
  • Mathematica
    b68Q[n_]:=Module[{b6=Union[IntegerDigits[n,6]],b8=Union[IntegerDigits[ n,8]]}, And@@Table[ MemberQ[b8,b6[[i]]],{i,Length[b6]}]]; Select[Range[ 1200],b68Q] (* Harvey P. Dale, Mar 24 2012 *)
Previous Showing 21-30 of 191 results. Next