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.

Previous Showing 21-25 of 25 results.

A261607 Initial digit of Fibonacci number F(n) in base 60.

Original entry on oeis.org

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 1, 2, 3, 6, 10, 16, 26, 43, 1, 1, 3, 4, 7, 12, 20, 33, 54, 1, 2, 3, 6, 10, 16, 26, 42, 1, 1, 3, 4, 7, 12, 20, 33, 54, 1, 2, 3, 6, 10, 16, 26, 42, 1, 1, 2, 4, 7, 12, 20, 33, 53, 1, 2, 3, 6, 9, 16, 25, 42, 1, 1, 2, 4, 7, 12
Offset: 0

Views

Author

Reinhard Zumkeller, Sep 09 2015

Keywords

Crossrefs

Programs

  • Haskell
    a261607 = last . a261575_row
    
  • Mathematica
    IntegerDigits[Fibonacci[Range[0, 75]], 60][[All, 1]] (* Michael De Vlieger, Jan 22 2022 *)
  • PARI
    a(n) = if (n, digits(fibonacci(n), 60)[1], 0); \\ Michel Marcus, Jan 22 2022

Formula

a(n) = A261575(n, A261585(n)-1).
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = Sum_{d=1..59} d*log(1+1/d)/log(60) = 13.92958... . - Amiram Eldar, Jan 12 2023
For n>9, a(n) = floor(60^{alpha*n-beta}), where alpha=log_60(phi), beta=log_60(5)/2, {x}=x-floor(x) denotes the fractional part of x, and phi = (1+sqrt(5))/2 = A001622. - Hans J. H. Tuenter, Aug 26 2025

A141053 Most-significant decimal digit of Fibonacci(5n+3).

Original entry on oeis.org

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

Views

Author

Paul Curtz, Aug 01 2008

Keywords

Comments

Leading digit of A134490(n).
From Johannes W. Meijer, Jul 06 2011: (Start)
The leading digit d, 1 <= d <= 9, of A141053 follows Benford’s Law. This law states that the probability for the leading digit is p(d) = log_10(1+1/d), see the examples.
We observe that the last digit of A134490(n), i.e. F(5*n+3) mod 10, leads to the Lucas sequence A000032(n) (mod 10), i.e. a repetitive sequence of 12 digits [2, 1, 3, 4, 7, 1, 8, 9, 7, 6, 3, 9] with p(0) = p(5) = 0, p(1) = p(3) = p(7) = p(9) = 1/6 and p(2) = p(4) = p(6) = p(8) = 1/12. This does not obey Benford’s Law, which would predict that the last digit would satisfy p(d) = 1/10, see the links. (End)

Examples

			From _Johannes W. Meijer_, Jul 06 2011: (Start)
d     p(N=2000) p(N=4000) p(N=6000) p(Benford)
1      0.29900   0.29950   0.30033   0.30103
2      0.17700   0.17675   0.17650   0.17609
3      0.12550   0.12525   0.12517   0.12494
4      0.09650   0.09675   0.09700   0.09691
5      0.07950   0.07950   0.07933   0.07918
6      0.06700   0.06675   0.06700   0.06695
7      0.05800   0.05825   0.05800   0.05799
8      0.05150   0.05125   0.05100   0.05115
9      0.04600   0.04600   0.04567   0.04576
Total  1.00000   1.00000   1.00000   1.00000 (End)
		

Crossrefs

Cf. A000045 (F(n)), A008963 (Initial digit F(n)), A105511-A105519, A003893 (F(n) mod 10), A130893, A186190 (First digit tribonacci), A008952 (Leading digit 2^n), A008905 (Leading digit n!), A045510, A112420 (Leading digit Collatz 3*n+1 starting with 1117065), A007524 (log_10(2)), A104140 (1-log_10(9)). - Johannes W. Meijer, Jul 06 2011

Programs

  • Maple
    A134490 := proc(n) combinat[fibonacci](5*n+3) ; end proc:
    A141053 := proc(n) convert(A134490(n),base,10) ; op(-1,%) ; end proc:
    seq(A141053(n),n=0..70) ; # R. J. Mathar, Jul 04 2011
  • Mathematica
    Table[IntegerDigits[Fibonacci[5n+3]][[1]],{n,0,70}] (* Harvey P. Dale, Jun 22 2025 *)

Formula

a(n) = floor(F(5*n+3)/10^(floor(log(F(5*n+3))/log(10)))). - Johannes W. Meijer, Jul 06 2011
For n>0, a(n) = floor(10^{alpha*n+beta}), where alpha=5*log_10(phi)-1, beta=log_10(1+2/sqrt(5)), {x}=x-floor(x) denotes the fractional part of x, log_10(phi) = A097348, and phi = (1+sqrt(5))/2 = A001622. - Hans J. H. Tuenter, Aug 27 2025

Extensions

Edited by Johannes W. Meijer, Jul 06 2011

A153726 Initial digit of Catalan number A000108(n).

Original entry on oeis.org

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

Views

Author

Omar E. Pol, Dec 30 2008

Keywords

Crossrefs

Programs

  • Mathematica
    First[IntegerDigits[#]]&/@CatalanNumber[Range[0,120]] (* Harvey P. Dale, Jan 20 2014 *)

Formula

a(n)=A000030(A000108(n)).

Extensions

More terms from Harvey P. Dale, Jan 20 2014

A367556 Comma transform of the Fibonacci numbers.

Original entry on oeis.org

1, 11, 12, 23, 35, 58, 81, 32, 13, 45, 58, 91, 42, 33, 76, 9, 71, 72, 44, 16, 51, 61, 12, 74, 87, 51, 31, 83, 15, 98, 1, 92, 93, 85, 79, 51, 22, 73, 96, 61, 51, 12, 64, 77, 31, 1, 32, 34, 67, 91, 52, 43, 95, 38, 21, 52, 73, 25, 99, 11, 2, 14, 16, 21, 31, 52, 84
Offset: 0

Views

Author

Alois P. Heinz, Nov 22 2023

Keywords

Comments

See A367360 for further information.

Crossrefs

Programs

  • Maple
    F:= combinat[fibonacci]:
    a:= n-> parse(cat(""||(F(n))[-1], ""||(F(n+1))[1])):
    seq(a(n), n=0..92);
  • Mathematica
    With[{nmax=100},Map[10Mod[#[[1]],10]+IntegerDigits[#[[2]]][[1]]&,Partition[Fibonacci[Range[0,nmax+1]],2,1]]] (* Paolo Xausa, Nov 24 2023 *)
  • Python
    from sympy import fibonacci
    from itertools import islice, pairwise, count
    def S(): yield from (fibonacci(i) for i in count(0))
    def C(g): # generator of comma transform of sequence passed as a generator
        yield from (10*(t%10) + int(str(u)[0]) for t, u in pairwise(g))
    def agen(): return C(S())
    print(list(islice(agen(), 67))) # Michael S. Branicky, Jan 05 2024

Formula

a(n) = 10 * A003893(n) + A008963(n+1).

A105150 Approximation to leading digit of n-th Fibonacci number.

Original entry on oeis.org

0, 1, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3, 5, 8, 1, 2, 3
Offset: 0

Views

Author

Reinhard Zumkeller, Apr 10 2005

Keywords

Comments

a(0) = 1, a(1) = a(2) = 1 and for n > 2:
a(n) = floor(w/10) + (w mod 10)*0^floor(w/10) where
w = (x+y)*0^(z-1) + y + z*0^floor((11-z)/10),
x = a(n-3), y = a(n-2) and z = a(n-1);
a(n) = A008963(n) = A000030(A000045(n)) for n<=14.

Examples

			n=11, x=2, y=3, z=5: w = (2+3) * 0^(5-1)+3+5*0^[(11-5)/10] = 5*0^4+3+5*0^0 = 0+3+5*1 = 8, a(11) = [8/10] + (8 mod 10) * 0^[8/10] = 0 + 8*0^0 = 8;
n=12, x=3, y=5, z=8: w = (3+5) * 0^(8-1)+5+8*0^[(11-8)/10] = 8*0^7+5+8*0^0 = 0+5+8*1 = 13, a(12) = [13/10] + (13 mod 10) * 0^[13/10] = 1 + 3*0^1 = 1;
n=13, x=5, y=8, z=1: w = (5+8) * 0^(1-1)+8+1*0^[(11-1)/10] = 13*0^0+8+1*0^1 = 13*1+8+1*0 = 21, a(13) = [21/10] + (21 mod 10) * 0^[21/10] = 2 + 1*0^2 = 2.
		
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