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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A102677 Number of digits >= 6 in decimal representation of n.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 0, 0, 0, 0, 0
Offset: 0

Views

Author

N. J. A. Sloane, Feb 03 2005

Keywords

Comments

a(n) = 0 iff n is in A007092 (numbers in base 6). - Bernard Schott, Feb 02 2023

Crossrefs

Programs

  • Maple
    p:=proc(n) local b,ct,j: b:=convert(n,base,10): ct:=0: for j from 1 to nops(b) do if b[j]>=6 then ct:=ct+1 else ct:=ct fi od: ct: end: seq(p(n),n=0..116); # Emeric Deutsch, Feb 23 2005
  • Mathematica
    Table[Total@ Take[Most@ DigitCount@ n, -4], {n, 0, 104}] (* Michael De Vlieger, Aug 17 2017 *)

Formula

From Hieronymus Fischer, Jun 10 2012: (Start)
a(n) = Sum_{j=1..m+1} (floor(n/10^j + 2/5) - floor(n/10^j)), where m = floor(log_10(n)).
G.f.: g(x) = (1/(1-x))*Sum_{j>=0} (x^(6*10^j) - x^(10*10^j))/(1-x^10^(j+1)). (End)

Extensions

More terms from Emeric Deutsch, Feb 23 2005

A309957 Product of digits of (n written in base 6).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 0, 2, 4, 6, 8, 10, 0, 3, 6, 9, 12, 15, 0, 4, 8, 12, 16, 20, 0, 5, 10, 15, 20, 25, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 0, 2, 4, 6, 8, 10, 0, 3, 6, 9, 12, 15, 0, 4, 8, 12, 16, 20, 0, 5, 10, 15, 20, 25, 0, 0, 0, 0, 0, 0, 0, 2, 4, 6, 8, 10, 0, 4, 8, 12, 16, 20, 0, 6, 12, 18, 24, 30, 0, 8, 16, 24, 32
Offset: 0

Views

Author

Ilya Gutkovskiy, Aug 24 2019

Keywords

Crossrefs

Programs

  • Magma
    [0] cat [&*Intseq(n,6):n in [1..100]]; // Marius A. Burtea, Aug 25 2019
  • Maple
    seq(convert(convert(n,base,6),`*`),n=0..100); # Robert Israel, Aug 24 2019
  • Mathematica
    Table[Times @@ IntegerDigits[n, 6], {n, 0, 100}]

Formula

G.f. A(x) satisfies: A(x) = x * (1 + 2*x + 3*x^2 + 4*x^3 + 5*x^4) * (1 + A(x^6)).

A353106 Base-6 representation of A007908(n).

Original entry on oeis.org

1, 20, 323, 5414, 133053, 2351320, 42243331, 1120335530, 20130035113, 5401014424514, 2343052550252003, 1114323133240053240, 321321022332303252301, 132140014431255340214310, 42015444551405453142112503
Offset: 1

Views

Author

Seiichi Manyama, Apr 23 2022

Keywords

Crossrefs

Programs

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

Formula

a(n) = A007092(A007908(n)).

A382416 Numbers with at least one zero in their base-6 representation.

Original entry on oeis.org

0, 6, 12, 18, 24, 30, 36, 37, 38, 39, 40, 41, 42, 48, 54, 60, 66, 72, 73, 74, 75, 76, 77, 78, 84, 90, 96, 102, 108, 109, 110, 111, 112, 113, 114, 120, 126, 132, 138, 144, 145, 146, 147, 148, 149, 150, 156, 162, 168, 174, 180, 181, 182, 183, 184, 185, 186, 192, 198
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), A382413 (base 7), A382417 (base 8), A382418 (base 9), A011540 (base 10).
Cf. A007092, A043369, A248910 (complement).

Programs

  • Mathematica
    Select[Range[0, 200], DigitCount[#, 6, 0] > 0 &]

A037398 Numbers k such that every base-6 digit of k is a base-7 digit of k.

Original entry on oeis.org

1, 2, 3, 4, 5, 7, 14, 21, 28, 35, 43, 68, 79, 86, 122, 123, 129, 165, 172, 208, 215, 246, 252, 260, 361, 373, 397, 425, 427, 431, 444, 445, 446, 469, 475, 476, 479, 481, 482, 504, 513, 520, 527, 556, 562, 583, 625, 696, 738, 756
Offset: 1

Views

Author

Keywords

Crossrefs

Programs

  • Haskell
    import Data.List ((\\), nub)
    a037398 n = a037398_list !! (n-1)
    a037398_list = filter f [1..] where
       f x = null $ nub (ds 6 x) \\ nub (ds 7 x)
       ds b x = if x > 0 then d : ds b x' else []  where (x', d) = divMod x b
    -- Reinhard Zumkeller, May 30 2013

A037400 Numbers k such that every base-6 digit of k is a base-9 digit of k.

Original entry on oeis.org

1, 2, 3, 4, 5, 21, 104, 108, 115, 129, 194, 212, 215, 252, 259, 271, 280, 352, 370, 388, 417, 504, 651, 756, 757, 758, 759, 760, 761, 762, 763, 777, 913, 922, 928, 932, 949, 976, 994, 1008, 1015, 1030, 1076, 1137, 1147, 1151, 1152
Offset: 1

Views

Author

Keywords

Crossrefs

Programs

  • Haskell
    import Data.List ((\\), nub)
    a037400 n = a037400_list !! (n-1)
    a037400_list = filter f [1..] where
       f x = null $ nub (ds 6 x) \\ nub (ds 9 x)
       ds b x = if x > 0 then d : ds b x' else []  where (x', d) = divMod x b
    -- Reinhard Zumkeller, May 30 2013

A043280 Maximal run length in base 6 representation of n.

Original entry on oeis.org

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

Views

Author

Keywords

Crossrefs

Cf. A007092.
Cf. A043276-A043290 for base-2 to base-16 analogs.

Programs

  • Mathematica
    A043280[n_]:=Max[Map[Length,Split[IntegerDigits[n,6]]]];Array[A043280,100] (* Paolo Xausa, Sep 27 2023 *)
  • PARI
    A043280(n, b=6)={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

A083900 Number of divisors of n with largest digit <= 5 (base 10).

Original entry on oeis.org

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

Views

Author

Reinhard Zumkeller, May 08 2003

Keywords

Crossrefs

Programs

Formula

a(n) = A083899(n) + A083892(n) = A083901(n) - A083893(n).
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = Sum_{k>=1} 1/A007092(k) = 5.25448032967060504709... . - Amiram Eldar, Jan 04 2024

A127113 n! in base 6.

Original entry on oeis.org

1, 1, 2, 10, 40, 320, 3200, 35200, 510400, 11440000, 205440000, 3543320000, 115310400000, 2505522400000, 104014341200000, 2440423132000000, 112255444052000000, 3300252314304000000, 143012413513200000000, 5313433311353200000000, 302523154413030400000000
Offset: 0

Views

Author

Artur Jasinski, Jan 05 2007

Keywords

Crossrefs

Programs

  • Mathematica
    FromDigits[IntegerDigits[#,6]]&/@(Range[0,30]!) (* Harvey P. Dale, Jun 18 2019 *)

Formula

a(n) = A007092(A000142(n)). - R. J. Mathar, Jun 09 2020

Extensions

More terms from Harvey P. Dale, Jun 18 2019

A032545 Integer part of decimal 'base-6 looking' numbers divided by their actual base-6 values, rounded down.

Original entry on oeis.org

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

Views

Author

Patrick De Geest, Apr 15 1998

Keywords

Crossrefs

See also A032532 for explanation.

Programs

  • Mathematica
    Array[IntegerPart[FromDigits[#2]/#1] & @@ {#, IntegerDigits[#, 6]} &, 105] (* Michael De Vlieger, Oct 06 2019 *)
  • PARI
    for(n=1,1e3,v=eval(Vec(Str(n)));if(vecmax(v)<6, print1(n\sum(i=1,#v,v[i]*6^(#v-i))", "))) \\ Charles R Greathouse IV, Apr 08 2012

Formula

a(n) = floor(A007092(n)/n). - Sean A. Irvine, Jun 22 2020
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