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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A212447 a(n) = floor(3n + log(3n)).

Original entry on oeis.org

4, 7, 11, 14, 17, 20, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 61, 64, 67, 70, 73, 76, 79, 82, 85, 88, 91, 94, 97, 100, 103, 106, 109, 112, 115, 118, 121, 124, 127, 130, 133, 136, 139, 142, 145, 148, 151, 155, 158, 161, 164, 167, 170, 173, 176, 179
Offset: 1

Views

Author

Mohammad K. Azarian, May 17 2012

Keywords

Crossrefs

Programs

A212448 Floor(4n + log(4n)).

Original entry on oeis.org

5, 10, 14, 18, 22, 27, 31, 35, 39, 43, 47, 51, 55, 60, 64, 68, 72, 76, 80, 84, 88, 92, 96, 100, 104, 108, 112, 116, 120, 124, 128, 132, 136, 140, 144, 148, 152, 157, 161, 165, 169, 173, 177, 181, 185, 189, 193, 197, 201, 205, 209, 213, 217, 221, 225, 229
Offset: 1

Views

Author

Mohammad K. Azarian, May 17 2012

Keywords

Crossrefs

Programs

A212449 Floor(5n + log(5n)).

Original entry on oeis.org

6, 12, 17, 22, 28, 33, 38, 43, 48, 53, 59, 64, 69, 74, 79, 84, 89, 94, 99, 104, 109, 114, 119, 124, 129, 134, 139, 144, 149, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, 245, 250, 255, 260, 265, 270, 275, 280, 285
Offset: 1

Views

Author

Mohammad K. Azarian, May 17 2012

Keywords

Crossrefs

Programs

A212450 a(n) = ceiling(n + log(n)).

Original entry on oeis.org

1, 3, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71
Offset: 1

Views

Author

Mohammad K. Azarian, May 17 2012

Keywords

Crossrefs

Programs

  • Magma
    [Ceiling(n + Log(n)): n in [1..80]]; // Vincenzo Librandi, Feb 14 2013
  • Mathematica
    Table[Ceiling[n + Log[n]], {n, 100}] (* T. D. Noe, May 21 2012 *)

A061282 Minimal number of steps to get from 0 to n by (a) adding 1 or (b) multiplying by 3. A stopping problem: begin with n and at each stage if a multiple of 3 divide by 3, otherwise subtract 1.

Original entry on oeis.org

0, 1, 2, 2, 3, 4, 3, 4, 5, 3, 4, 5, 4, 5, 6, 5, 6, 7, 4, 5, 6, 5, 6, 7, 6, 7, 8, 4, 5, 6, 5, 6, 7, 6, 7, 8, 5, 6, 7, 6, 7, 8, 7, 8, 9, 6, 7, 8, 7, 8, 9, 8, 9, 10, 5, 6, 7, 6, 7, 8, 7, 8, 9, 6, 7, 8, 7, 8, 9, 8, 9, 10, 7, 8, 9, 8, 9, 10, 9, 10, 11, 5, 6, 7, 6, 7, 8, 7, 8, 9, 6, 7, 8, 7, 8, 9, 8, 9, 10, 7, 8
Offset: 0

Views

Author

Henry Bottomley, Jun 06 2001

Keywords

Comments

n > 0 occurs A001590(n+2) times in this sequence. - Peter Kagey, Jul 19 2015
a(n) gives the number of iterations of A260316 to reach 0. - Peter Kagey, Jul 22 2015

Examples

			a(25)=7 since 25=((0+1+1)*3+1+1)*3+1.
		

Crossrefs

Analogous sequences with a different multiplier k: A056792 (k=2), A260112 (k=4).

Programs

  • Haskell
    c i = if i `mod` 3 == 0 then i `div` 3 else i - 1
    b 0 foldCount = foldCount
    b sheetCount foldCount = b (c sheetCount) (foldCount + 1)
    a061282 n = b n 0 -- Peter Kagey, Sep 02 2015
  • Maple
    a:= n-> (l-> nops(l)+add(i, i=l)-1)(convert(n, base, 3)):
    seq(a(n), n=0..105);  # Alois P. Heinz, Jul 16 2015
  • PARI
    a(n)=sumdigits(n,3)+#digits(n,3)-1 \\ Charles R Greathouse IV, Jul 16 2015
    

Formula

a(n) = A062153(n) + A053735(n) = (number of base 3 digits of n) + (sum of base 3 digits of n)-1. a(3n) = a(n)+1, a(3n+1) = a(n)+2, a(3n+2) = a(n)+3; a(0)=0, a(1)=1, a(2)=2.

A054965 Beatty sequence for log_3(10), i.e., for 1/log_10(3); so largest exponent of 3 which produces an n-digit decimal number.

Original entry on oeis.org

2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 111, 113, 115, 117, 119, 121, 123, 125, 127, 129, 132, 134, 136
Offset: 1

Views

Author

Henry Bottomley, Dec 13 2002

Keywords

Examples

			log_10(3) = 0.477121... so a(11) = floor(11/0.477121...) = floor(23.0549...) = 23; 3^23 = 94143178827 is the largest 11 decimal digit power of 3.
		

Crossrefs

Programs

  • Mathematica
    Floor[Range[100]*Log[3, 10]] (* Paolo Xausa, Jul 11 2024 *)
  • PARI
    a(n) = n*log(10)\log(3); \\ Michel Marcus, Aug 03 2017

Formula

a(n) = floor(n/log_10(3)) = log_3(A074118(n)) = A062153(A074118(n)).

A065335 3-exponents to represent 3-smooth numbers (A065332).

Original entry on oeis.org

0, 0, 1, 0, 0, 1, 0, 0, 2, 0, 0, 1, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 1, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0
Offset: 1

Views

Author

Reinhard Zumkeller, Oct 29 2001

Keywords

Crossrefs

Programs

  • Mathematica
    a[n_] := If[n/2^IntegerExponent[n, 2]/3^(e = IntegerExponent[n, 3]) == 1, e, 0]; Array[a, 100] (* Amiram Eldar, Feb 21 2021 *)

Formula

a(n) = A007949(n) * A065333(n).
a(n) = log_3(n / A006519(n)), where log_3 = A062153. For k > 0 with A065332(k) > 0: A065332(k) = (2^A065334(k)) * (3^a(k)).

A105202 Irregular triangle read by rows: row n gives the word f(f(f(...(1)))) [with n applications of f], where f is the morphism 1->{1,2,1}, 2->{2,3,2}, 3->{3,1,3}.

Original entry on oeis.org

1, 1, 2, 1, 1, 2, 1, 2, 3, 2, 1, 2, 1, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 3, 1, 3, 2, 3, 2, 1, 2, 1, 2, 3, 2, 1, 2, 1, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 3, 1, 3, 2, 3, 2, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 3, 1, 3, 2, 3, 2, 3, 1, 3, 1, 2, 1, 3, 1, 3, 2, 3, 2, 3, 1, 3, 2, 3, 2, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 3
Offset: 0

Views

Author

Roger L. Bagula, Apr 09 2005

Keywords

Comments

Row n contains 3^n symbols.

Examples

			From _Antti Karttunen_, Aug 12 2017: (Start)
The rows 0 .. 3 of this irregular triangle:
  1
  1;2;1
  1 2 1;2 3 2;1 2 1;
  1 2 1 2 3 2 1 2 1;2 3 2 3 1 3 2 3 2;1 2 1 2 3 2 1 2 1
(End)
		

Crossrefs

Each row is a prefix of A105203.

Programs

  • Mathematica
    f[n_] := Nest[ Flatten[ # /. {1 -> {1, 2, 1}, 2 -> {2, 3, 2}, 3 -> {3, 1, 3}}] &, {1}, n]; Flatten[ Table[ f[n], {n, 0, 4}]] (* Robert G. Wilson v, Apr 12 2005 *)

Formula

Let r = A062153(1+(2*n)) [index of the row], let c = n - A003462(r) [index of the column], then a(n) = 1 + (a(A003462(r-1)+floor(c/3)) mod 3) if n ≡ 2 mod 3, otherwise a(n) = a(A003462(r-1)+floor(c/3)). - Antti Karttunen, Aug 12 2017

Extensions

More terms from Robert G. Wilson v, Apr 12 2005

A105203 Trajectory of 1 under the morphism f: 1->{1,2,1}, 2->{2,3,2}, 3->{3,1,3}.

Original entry on oeis.org

1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 3, 1, 3, 2, 3, 2, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 3, 1, 3, 2, 3, 2, 3, 1, 3, 1, 2, 1, 3, 1, 3, 2, 3, 2, 3, 1, 3, 2, 3, 2, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 3, 1, 3, 2, 3, 2, 1, 2, 1, 2, 3, 2, 1, 2, 1, 2, 3, 2, 3, 1, 3, 2, 3, 2, 3, 1, 3, 1, 2, 1, 3, 1, 3, 2, 3, 2, 3, 1, 3
Offset: 0

Views

Author

Roger L. Bagula, Apr 09 2005

Keywords

Crossrefs

Programs

Formula

a(0) = 1; and for n > 1, a(n) = A105202(n+A003462(1+A062153(n))). - Antti Karttunen, Aug 12 2017

Extensions

More terms from Robert G. Wilson v, Apr 12 2005

A329194 a(n) = floor(log_3(n^2)) = floor(2 log_3(n)).

Original entry on oeis.org

0, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8
Offset: 1

Views

Author

M. F. Hasler, Nov 07 2019

Keywords

Crossrefs

Cf. A000290 (n^2), A062153 (log_3), A329202 (log_2(n^2)), A329193 (log_2(n^3)).

Programs

  • Mathematica
    Table[Floor[Log[3,n^2]],{n,120}] (* Harvey P. Dale, May 04 2025 *)
  • PARI
    apply( A329194(n)=logint(n^2,3), [1..99])

Formula

2*A062153(n) <= a(n) = floor(log_3(n^2)) = A062153(A000290(n)).
Previous Showing 11-20 of 29 results. Next