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.

Showing 1-10 of 23 results. Next

A007524 Decimal expansion of log_10(2).

Original entry on oeis.org

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

Views

Author

Keywords

Comments

Log_10(2) is the probability that 1 be first significant digit occurring in data collections (Benford's law). - Lekraj Beedassy, Jan 21 2005
When adding two sound power sources of x decibels, the resulting sound power is x + 10*log_10(2), that is x + 3.01... decibels. - Jean-François Alcover, Jun 21 2013
In engineering (all branches, but particularly electronic and electrical) power and amplitude ratios are measured rigorously in decibels (dB). This constant, with offset 1 (i.e., 3.01... = 10*A007524) is the dB equivalent of a 2:1 power ratio or, equivalently, sqrt(2):1 amplitude ratio. - Stanislav Sykora, Dec 11 2013

Examples

			0.3010299956639811952137388947244930267681898814621085413104274611271...
		

References

  • John H. Conway and Richard K. Guy, The Book of Numbers, New York: Springer-Verlag, 1996. See pp. 24, 249.
  • T. Hill, "Manipulation, or the First Significant Numeral Determines the Law", in 'La Recherche', No. 2 1999 pp. 72-76 (or No. 116 1999 pp. 72-75), Paris.
  • M. E. Lines, A Number For Your Thought, pp. 43-52 Institute of Physics Pub. London 1990.
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
  • I. Stewart, L'univers des nombres, "1 est plus probable que 9", pp. 57-61, Belin-Pour La Science, Paris 2000.
  • David Wells, The Penguin Dictionary of Curious and Interesting Numbers. Penguin Books, NY, 1986, Revised edition 1987, p. 27.

Crossrefs

Cf. decimal expansion of log_10(m): this sequence, A114490 (m = 3), A114493 (m = 4), A153268 (m = 5), A153496 (m = 6), A153620 (m = 7), A153790 (m = 8), A104139 (m = 9), A154182 (m = 11), A154203 (m = 12), A154368 (m = 13), A154478 (m = 14), A154580 (m = 15), A154794 (m = 16), A154860 (m = 17), A154953 (m = 18), A155062 (m = 19), A155522 (m = 20), A155677 (m = 21), A155746 (m = 22), A155830 (m = 23), A155979 (m = 24).

Programs

  • Mathematica
    RealDigits[Log[10, 2], 10, 120][[1]] (* Harvey P. Dale, Dec 19 2011 *)
  • PARI
    default(realprecision, 20080); x=log(2)/log(10); d=0; for (n=0, 20000, x=(x-d)*10; d=floor(x); write("b007524.txt", n, " ", d)); \\ Harry J. Smith, Apr 15 2009

Formula

log_10(2) = log(2)/log(10) = log(2)/(log(2) + log(5)).
Equals 1/A020862. - R. J. Mathar, Jul 31 2025

Extensions

Definition corrected by Franklin T. Adams-Watters, Apr 13 2006
Final digits of sequence corrected using the b-file. - N. J. A. Sloane, Aug 30 2009

A038772 Numbers not divisible by any of their digits.

Original entry on oeis.org

23, 27, 29, 34, 37, 38, 43, 46, 47, 49, 53, 54, 56, 57, 58, 59, 67, 68, 69, 73, 74, 76, 78, 79, 83, 86, 87, 89, 94, 97, 98, 203, 207, 209, 223, 227, 229, 233, 239, 247, 249, 253, 257, 259, 263, 267, 269, 277, 283, 289, 293, 299, 307, 308, 323, 329, 334, 337, 338
Offset: 1

Views

Author

Henry Bottomley, May 04 2000

Keywords

Comments

A038769(a(n)) = 0; complement of A038770.
This is a regular language when written in decimal, though the minimal regular expression is probably thousands of characters long. - Charles R Greathouse IV, Aug 19 2011
Exponential density 0.954... = A104139. Asymptotically 8/35 * n^0.954... + O(n^0.903...) members up to n. - Charles R Greathouse IV, Jul 22 2012

Examples

			34 is divisible by neither 3 nor 4.
35 is excluded because 5 is a divisor of 35, but 37 is included because neither 3 nor 7 is a divisor of 37
		

Crossrefs

Cf. A327561 (counts), A038770 (complement).
Cf. also A034709, A034837, A038769.

Programs

  • Haskell
    import Data.Char (digitToInt)
    a038772 n = a038772_list !! (n-1)
    a038772_list = filter p [1..] where
       p n = all (> 0) $ map ((mod n) . digitToInt) $ filter (> '0') $ show n
    -- Reinhard Zumkeller, Jun 19 2011
    
  • Magma
    [k:k in [1..340]| forall{c:c in Set(Intseq(k)) diff {0}|k mod c ne 0}]; // Marius A. Burtea, Dec 22 2019
    
  • Mathematica
    nddQ[n_]:=Module[{idn=DeleteCases[IntegerDigits[n],0]},And@@Table[ !Divisible[n, idn[[i]]],{i,Length[idn]}]]; Select[Range[350],nddQ] (* Harvey P. Dale, Nov 01 2011 *)
  • PARI
    is(n)=my(v=vecsort(eval(Vec(Str(n))), , 8)); for(i=if(v[1], 1, 2), #v, if(n%v[i]==0, return(0))); 1 \\ Charles R Greathouse IV, Jul 22 2011
    
  • Python
    def ok(n): return not any(n%int(d) == 0 for d in str(n) if d != '0')
    print(list(filter(ok, range(1, 339)))) # Michael S. Branicky, May 20 2021

Extensions

Edited by N. J. A. Sloane, Nov 17 2008 at the suggestion of R. J. Mathar

A154580 Decimal expansion of log_10 (15).

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane, Oct 30 2009

Keywords

Examples

			1.1760912590556812420812890085306222824319389827285873235194...
		

Crossrefs

Cf. decimal expansion of log_10(m): A007524 (m=2), A114490 (m=3), A114493 (m=4), A153268 (m=5), A153496 (m=6), A153620 (m=7), A153790 (m=8), A104139 (m=9), A154182 (m=11), A154203 (m=12), A154368 (m=13), A154478 (m=14), this sequence, A154794 (m=16), A154860 (m=17), A154953 (m=18), A155062 (m=19), A155522 (m=20), A155677 (m=21), A155746 (m=22), A155830 (m=23), A155979 (m=24).

Programs

Formula

Equals A016638 / A002392 = (1+A152914)/(1+A152675). - R. J. Mathar, Jul 29 2024

A114490 Decimal expansion of log_10(3).

Original entry on oeis.org

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

Views

Author

Eric W. Weisstein, Dec 01 2005

Keywords

Examples

			0.477121254...
		

Crossrefs

Cf. A114473.
Cf. decimal expansion of log_10(m): A007524 (m=2), this sequence, A114493 (m=4), A153268 (m=5), A153496 (m=6), A153620 (m=7), A153790 (m=8), A104139 (m=9), A154182 (m=11), A154203 (m=12), A154368 (m=13), A154478 (m=14), A154580 (m=15), A154794 (m=16), A154860 (m=17), A154953 (m=18), A155062 (m=19), A155522 (m=20), A155677 (m=21), A155746 (m=22), A155830 (m=23), A155979 (m=24).

Programs

Formula

Equals 1/A152566. - R. J. Mathar, Jul 31 2025

A154203 Decimal expansion of log_10 (12).

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane, Oct 30 2009

Keywords

Examples

			1.0791812460476248277225056927041013627365086271149129474507...
		

Crossrefs

Cf. decimal expansion of log_10(m): A007524 (m=2), A114490 (m=3), A114493 (m=4), A153268 (m=5), A153496 (m=6), A153620 (m=7), A153790 (m=8), A104139 (m=9), A154182 (m=11), this sequence, A154368 (m=13), A154478 (m=14), A154580 (m=15), A154794 (m=16), A154860 (m=17), A154953 (m=18), A155062 (m=19), A155522 (m=20), A155677 (m=21), A155746 (m=22), A155830 (m=23), A155979 (m=24).

Programs

Formula

Equals A007524 + A153596. - R. J. Mathar, Jan 07 2021

A114493 Decimal expansion of log_10(4).

Original entry on oeis.org

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

Views

Author

Eric W. Weisstein, Dec 01 2005

Keywords

Comments

In engineering (all branches, but particularly electronic and electrical) power and amplitude ratios are measured rigorously in decibels (dB). This constant, with offset 1 (i.e., 6.02... = 10*A114493) is the dB equivalent of a 2:1 amplitude ratio or, equivalently, 4:1 power ratio. - Stanislav Sykora, Dec 11 2013

Examples

			0.602059991...
		

Crossrefs

Cf. decimal expansion of log_10(m): A007524 (m=2), A114490 (m=3), this sequence, A153268 (m=5), A153496 (m=6), A153620 (m=7), A153790 (m=8), A104139 (m=9), A154182 (m=11), A154203 (m=12), A154368 (m=13), A154478 (m=14), A154580 (m=15), A154794 (m=16), A154860 (m=17), A154953 (m=18), A155062 (m=19), A155522 (m=20), A155677 (m=21), A155746 (m=22), A155830 (m=23), A155979 (m=24).

Programs

Formula

A016627 divided by A002392. Two times A007524. - R. J. Mathar, Feb 21 2013
Equals 1/A154155. - R. J. Mathar, Jul 31 2025

A153620 Decimal expansion of log_10 (7).

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane, Oct 30 2009

Keywords

Examples

			.84509804001425683071221625859263619348357239632396540650363...
		

Crossrefs

Cf. decimal expansion of log_10(m): A007524 (m=2), A114490 (m=3), A114493 (m=4), A153268 (m=5), A153496 (m=6), this sequence, A153790 (m=8), A104139 (m=9), A154182 (m=11), A154203 (m=12), A154368 (m=13), A154478 (m=14), A154580 (m=15), A154794 (m=16), A154860 (m=17), A154953 (m=18), A155062 (m=19), A155522 (m=20), A155677 (m=21), A155746 (m=22), A155830 (m=23), A155979 (m=24).

Programs

A153496 Decimal expansion of log_10 (6).

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane, Oct 30 2009

Keywords

Examples

			.77815125038364363250876679797960833596831874565280440614029...
		

Crossrefs

Cf. decimal expansion of log_10(m): A007524 (m=2), A114490 (m=3), A114493 (m=4), A153268 (m=5), this sequence, A153620 (m=7), A153790 (m=8), A104139 (m=9), A154182 (m=11), A154203 (m=12), A154368 (m=13), A154478 (m=14), A154580 (m=15), A154794 (m=16), A154860 (m=17), A154953 (m=18), A155062 (m=19), A155522 (m=20), A155677 (m=21), A155746 (m=22), A155830 (m=23), A155979 (m=24).

Programs

Formula

Equals 1/A154157. - R. J. Mathar, Jul 31 2025

A154182 Decimal expansion of log_10 (11).

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane, Oct 30 2009

Keywords

Examples

			1.0413926851582250407501999712430242417067021904664530945965...
		

Crossrefs

Cf. decimal expansion of log_10(m): A007524 (m=2), A114490 (m=3), A114493 (m=4), A153268 (m=5), A153496 (m=6), A153620 (m=7), A153790 (m=8), A104139 (m=9), this sequence, A154203 (m=12), A154368 (m=13), A154478 (m=14), A154580 (m=15), A154794 (m=16), A154860 (m=17), A154953 (m=18), A155062 (m=19), A155522 (m=20), A155677 (m=21), A155746 (m=22), A155830 (m=23), A155979 (m=24).

Programs

A153268 Decimal expansion of log_10 (5).

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane, Oct 30 2009

Keywords

Examples

			.69897000433601880478626110527550697323181011853789145868957...
		

Crossrefs

Cf. decimal expansion of log_10(m): A007524 (m=2), A114490 (m=3), A114493 (m=4), this sequence, A153496 (m=6), A153620 (m=7), A153790 (m=8), A104139 (m=9), A154182 (m=11), A154203 (m=12), A154368 (m=13), A154478 (m=14), A154580 (m=15), A154794 (m=16), A154860 (m=17), A154953 (m=18), A155062 (m=19), A155522 (m=20), A155677 (m=21), A155746 (m=22), A155830 (m=23), A155979 (m=24).

Programs

Formula

Equals 1/A154156. - R. J. Mathar, Jul 31 2025
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