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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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 *)

A136381 Sequence A136380 shown in octal base.

Original entry on oeis.org

30, 240, 27300, 275332400, 27624273321353000, 277524424264553332245513535524000, 27762724550512424245125524562733322130552452655353526564552130000, 277751305605652455261312526532424241366545132655245452272135533332224427213254552451226545102753535225125262712455250570562640000
Offset: 1

Views

Author

Antti Karttunen, Dec 29 2007

Keywords

Crossrefs

Cf. A036285, A136383 (shifted two bits right), A136385.

Formula

a(n) = A007094(A136380(n)).

A136383 Sequence A136382 shown in octal base.

Original entry on oeis.org

6, 50, 5660, 57266500, 5745056664272600, 57725105055132666451322727325000, 5774565132122505051225325134566664426132512553272725535132426000, 57772261341352513254262525526505050275531226553251312456427326666445105642653132512245531220572727245225254562513252136134550000
Offset: 1

Views

Author

Antti Karttunen, Dec 29 2007

Keywords

Crossrefs

Cf. A036285, A136381 (shifted two bits left), A136385.

Formula

a(n) = A007094(A136382(n)).

A136385 Sequence A136384 shown in octal base.

Original entry on oeis.org

4, 60, 6440, 65444600, 6506064447454400, 65231606066154444716234545546000, 6527131623634606061431546150644447033623163115454546626154744000, 65254336276263162310334631144606060326621433115461563064745544444706171303315623163471156340654545471431467134615463624150660000
Offset: 1

Views

Author

Antti Karttunen, Dec 29 2007

Keywords

Crossrefs

Formula

a(n) = A007094(A136384(n)).

A217009 Multiples of 7 in base 8.

Original entry on oeis.org

7, 16, 25, 34, 43, 52, 61, 70, 77, 106, 115, 124, 133, 142, 151, 160, 167, 176, 205, 214, 223, 232, 241, 250, 257, 266, 275, 304, 313, 322, 331, 340, 347, 356, 365, 374, 403, 412, 421, 430, 437, 446, 455, 464, 473, 502, 511, 520, 527, 536, 545, 554, 563
Offset: 1

Views

Author

Jon Perry, Sep 23 2012

Keywords

Comments

Digit sum is always divisible by 7.
Reinterpreting this sequence in base 10, these are numbers of the form 9n + 7 but with all numbers containing 8s and/or 9s removed. - Alonso del Arte, Sep 23 2012

Examples

			a(10) = 106 because 7 * 10 = 70, or 1 * 8^2 + 0 * 8^1 + 6 * 8^0 = 64 + 6 = 106_8.
		

Crossrefs

Programs

  • JavaScript
    k = 7;
    for (i = 1; i <= 200; i++) {
    x = i * k;
    document.write(x.toString(k + 1) + ", ");
    }
  • Mathematica
    Table[BaseForm[7*n, 8], {n, 100}] (* Alonso del Arte, Sep 23 2012 *)
    Select[9*Range[0, 99] + 7, DigitCount[#, 10, 8] == 0 && DigitCount[#, 10, 9] == 0 &] (* Alonso del Arte, Sep 23 2012 *)
    Table[FromDigits[IntegerDigits[7*n, 8]], {n, 100}] (* T. D. Noe, Sep 24 2012 *)

Formula

a(n) = A007094(A008589(n)). -

A382417 Numbers with at least one zero in their base-8 representation.

Original entry on oeis.org

0, 8, 16, 24, 32, 40, 48, 56, 64, 65, 66, 67, 68, 69, 70, 71, 72, 80, 88, 96, 104, 112, 120, 128, 129, 130, 131, 132, 133, 134, 135, 136, 144, 152, 160, 168, 176, 184, 192, 193, 194, 195, 196, 197, 198, 199, 200, 208, 216, 224, 232, 240, 248, 256, 257, 258, 259, 260
Offset: 1

Views

Author

Paolo Xausa, Mar 25 2025

Keywords

Crossrefs

Cf. analogous sequences in other bases: A062289 (base 2), A081605 (base 3), A196032 (base 4), A382415 (base 5), A382416 (base 6), A382413 (base 7), A382418 (base 9), A011540 (base 10).
Cf. A007094, A043421, A255805 (complement).

Programs

  • Mathematica
    Select[Range[0, 300], DigitCount[#, 8, 0] > 0 &]

A004682 Primes written in base 8.

Original entry on oeis.org

2, 3, 5, 7, 13, 15, 21, 23, 27, 35, 37, 45, 51, 53, 57, 65, 73, 75, 103, 107, 111, 117, 123, 131, 141, 145, 147, 153, 155, 161, 177, 203, 211, 213, 225, 227, 235, 243, 247, 255, 263, 265, 277, 301, 305, 307, 323, 337, 343, 345, 351, 357, 361, 373, 401, 407, 415, 417
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. similar sequences listed in A004680.
Cf. A007094.

Programs

  • Magma
    [Seqint(Intseq(NthPrime(n),8)): n in [1..60]]; // G. C. Greubel, Oct 10 2018
  • Mathematica
    FromDigits/@IntegerDigits[Prime[Range[50]], 8] (* Vincenzo Librandi, Sep 03 2016 *)
  • PARI
    a(n)=subst(Pol(digits(prime(n),8)),'x,10) \\ Charles R Greathouse IV, Nov 06 2013
    
  • PARI
    vector(60, n, fromdigits(digits(prime(n), 8))) \\ G. C. Greubel, Oct 10 2018
    

Formula

a(n) = A007094(prime(n)). - Michel Marcus, Sep 03 2016

A037402 Numbers k such that every base-7 digit of k is a base-8 digit of k.

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 8, 16, 24, 32, 40, 48, 57, 85, 94, 106, 114, 133, 142, 163, 171, 196, 204, 212, 220, 224, 225, 226, 227, 228, 229, 230, 236, 244, 277, 285, 305, 334, 342, 385, 392, 401, 540, 546, 547, 550, 597, 620, 629, 646, 688
Offset: 1

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Author

Keywords

Crossrefs

Programs

  • Haskell
    import Data.List ((\\), nub)
    a037402 n = a037402_list !! (n-1)
    a037402_list = filter f [1..] where
       f x = null $ nub (ds 7 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
    b7b8Q[n_]:=Module[{idn7=Union[IntegerDigits[n,7]]},Intersection[ idn7, Union[ IntegerDigits[n,8]]]==idn7]; Select[Range[700],b7b8Q] (* Harvey P. Dale, Dec 15 2013 *)

A043282 Maximal run length in base 8 representation of n.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 1, 1, 1, 1, 2, 3, 2, 2, 2, 2, 2, 2, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A007094 (base 8).
Cf. A043276-A043290 for base-2 to base-16 analogs.

Programs

  • Mathematica
    A043282[n_]:=Max[Map[Length,Split[IntegerDigits[n,8]]]];Array[A043282,100] (* Paolo Xausa, Sep 27 2023 *)
  • PARI
    A043282(n, b=8)={my(m, c=1); while(n>0, n%b==(n\=b)%b && c++ && next; m=max(m, c); c=1); m} \\ M. F. Hasler, Jul 23 2013
    
  • Python
    from itertools import groupby
    def A043282(n): return max(len(list(g)) for k, g in groupby(oct(n)[2:])) # Chai Wah Wu, Mar 09 2023

A083902 Number of divisors of n with the largest digit of the divisor <= 7 (base 10).

Original entry on oeis.org

1, 2, 2, 3, 2, 4, 2, 3, 2, 4, 2, 6, 2, 4, 4, 4, 2, 4, 1, 6, 4, 4, 2, 7, 3, 4, 3, 5, 1, 8, 2, 5, 4, 4, 4, 7, 2, 2, 3, 7, 2, 8, 2, 6, 5, 4, 2, 8, 2, 6, 4, 6, 2, 6, 4, 6, 3, 2, 1, 12, 2, 4, 5, 6, 4, 8, 2, 5, 3, 8, 2, 9, 2, 4, 6, 4, 4, 6, 1, 8, 3, 3, 1, 10, 3, 3, 2, 6, 1, 9, 3, 5, 3, 3, 2, 9, 1, 4, 4, 9, 2, 8, 2, 7, 8
Offset: 1

Views

Author

Reinhard Zumkeller, May 08 2003

Keywords

Crossrefs

Programs

Formula

a(n) = A083901(n) + A083894(n) = A083903(n) - A083895(n).
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = Sum_{k>=1} 1/A007094(k) = 11.2915816168324913817... . - Amiram Eldar, Jan 04 2024

Extensions

Definition clarified by Harvey P. Dale, Nov 01 2022
Previous Showing 31-40 of 239 results. Next