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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A000867 Numbers beginning with letter 'f' in English.

Original entry on oeis.org

4, 5, 14, 15, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 400, 401, 402, 403, 404, 405, 406, 407, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420, 421, 422, 423, 424, 425, 426, 427, 428, 429, 430, 431, 432
Offset: 1

Views

Author

N. J. A. Sloane

Keywords

Links

Crossrefs

Subsequence of A125299.
Cf. A000865, A000870, A000873, A000981, A006092.

Programs

  • Mathematica
    Select[Range[1000], First[Characters[IntegerName[#,"Words"]]]=="f"&] (* James C. McMahon, Dec 11 2023 *)

Extensions

More terms from John Cerkan, Feb 11 2017

A000870 Numbers beginning with letter 's' in English.

Original entry on oeis.org

6, 7, 16, 17, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 600, 601, 602, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612, 613, 614, 615, 616, 617, 618, 619, 620
Offset: 1

Views

Author

N. J. A. Sloane

Keywords

Links

Crossrefs

Subsequence of A125299.
Cf. A000865, A000867, A000873, A000981, A006092.

Programs

  • Mathematica
    Select[Range[10^3], Function[d, Or[And[Mod[IntegerLength@ #, 3] == 2, MemberQ[{16, 17}, FromDigits@ Take[d, 2]]], MemberQ[{6, 7}, First@ d]]]@ IntegerDigits@ # &] (* Michael De Vlieger, Feb 13 2017 *)

Extensions

Edited by John Cerkan, Feb 13 2017

A000873 Numbers beginning with letter 'e' in English.

Original entry on oeis.org

8, 11, 18, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 800, 801, 802, 803, 804, 805, 806, 807, 808, 809, 810, 811, 812, 813, 814, 815, 816, 817, 818, 819, 820, 821, 822, 823, 824, 825, 826, 827, 828, 829
Offset: 1

Views

Author

N. J. A. Sloane

Keywords

Links

Crossrefs

Subsequence of A000852.
Cf. A000865, A000867, A000870, A000981, A006092.

Programs

  • Mathematica
    Select[Range[10^3], Function[d, Or[And[Mod[IntegerLength@ #, 3] == 2, MemberQ[{11, 18}, FromDigits@ Take[d, 2]]], First@ d == 8]]@ IntegerDigits@ # &] (* Michael De Vlieger, Feb 13 2017 *)

Extensions

Corrected by Sam Alexander (pink2001x(AT)hotmail.com)
Edited by John Cerkan, Feb 13 2017

A008777 Number of dots and dashes used when representing n-th letter in Morse code.

Original entry on oeis.org

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

Views

Author

N. J. A. Sloane

Keywords

Comments

Number of digits of A059852 written in base 3.

Crossrefs

Cf. A059852 (Morse code for letters A-Z, read in base 3).

Programs

Formula

a(n) = floor(log_3(A059852(n))) + 1. - M. F. Hasler, Jun 22 2020

A010691 Period 2: repeat (1,10).

Original entry on oeis.org

1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10, 1, 10
Offset: 0

Views

Author

N. J. A. Sloane

Keywords

Comments

Regular continued fraction of (5+sqrt 35)/10. - R. J. Mathar, Nov 21 2011
Sequence is an infinite palindrome in two ways (numbers and English names): ONE, TEN, ONE, TEN, ONE, TEN, ONE, ... . - Eric Angelini, Sep 16 2023

Links

Crossrefs

Cf. A036117, A070341, A168429, A070367, A070392, A070404, A048271, A187466.

Programs

  • Magma
    [10^n mod 11: n in [0..80]]; // Vincenzo Librandi, Aug 24 2011
  • Maple
    g:=(1+10*z)/((1-z^2)): gser:=series(g, z=0, 66): seq((coeff(gser, z, n)), n=0..65); # Zerinvary Lajos, Feb 25 2009
  • Mathematica
    PadRight[{},100,{1,10}] (* Harvey P. Dale, Aug 27 2013 *)

Formula

a(n) = -9/2*(-1)^n + 11/2.
G.f.: (1+10*z)/(1-z^2). - Zerinvary Lajos, Feb 25 2009
a(n) = 10^n mod 11. - M. F. Hasler, Mar 10 2011
From Nicolas Bělohoubek, Nov 11 2021: (Start)
a(n) = 10/a(n-1). See also A010695.
a(n) = 11 - a(n-1). See also A010712. (End)

A014254 Liponombres: numbers whose French name does not contain the letter "e".

Original entry on oeis.org

1, 3, 5, 6, 8, 10, 18, 20, 23, 25, 26, 28, 1000000, 1000001, 1000003, 1000005, 1000006, 1000008, 1000010, 1000018, 1000020, 1000023, 1000025, 1000026, 1000028, 3000000, 3000001, 3000003, 3000005, 3000006, 3000008, 3000010
Offset: 1

Views

Author

Olivier Gérard

Keywords

Comments

In French also called: les nombres "évites" ou "apparés".
Could also be called les nombres "epers". - Benoit Cloitre, May 05 2003
French version of eban numbers (A006933): no "e" in name of number in French - "e" perd ("e" lost)!

Examples

			a(1) = 1 ("un"), a(2) = 3 ("trois", not "dEux")

References

  • Georges Perec, La disparition, Editions Gallimard, Paris, 1969; English translation: A Void, Harvill, 1994. (A novel that does not use the letter "e". These numbers are not mentioned, however.)

Links

Crossrefs

Cf. A006933, A050280 (primes); A167507, A139212, A007005, A139121, A233185.

Programs

Extensions

Additional comments from Bruno Salvy (Bruno.Salvy(AT)inria.fr) and Nicolas Graner (Nicolas.Graner(AT)cri.u-psud.fr), May 11 2003
Corrected by Don Reble, Nov 19 2006
Edited by M. F. Hasler, Nov 11 2015

A014388 a(2n-1) = n+2, a(2n) = smallest number requiring n+2 letters in English.

Original entry on oeis.org

3, 1, 4, 4, 5, 3, 6, 11, 7, 15, 8, 13, 9, 17, 10, 24, 11, 23, 12, 73, 13, 3000, 14, 11000, 15, 15000, 16, 101, 17, 104, 18, 103, 19, 111, 20, 115, 21, 113, 22, 117, 23, 124, 24, 123, 25, 173, 26, 323, 27, 373, 28, 1104, 29, 1103, 30, 1111, 31
Offset: 1

Views

Author

Jacques Haubrich (jhaubrich(AT)freeler.nl)

Keywords

Comments

Uses number forms containing "and"; that is, "one hundred and one" rather than "one hundred one". - Sean A. Irvine, Oct 20 2018

Crossrefs

Cf. A000916, A001166, A014388, A045494, A045495.

Extensions

More terms from Sean A. Irvine, Oct 20 2018

A019440 Integers in alphabetical order in British English.

Original entry on oeis.org

8, 8000000000000, 8000000000008, 8000000000018, 8000000000080, 8000000000088, 8000000000085
Offset: 1

Views

Author

N. J. A. Sloane, Neil Fernandez

Keywords

Examples

			The list begins "eight", "eight billion", "eight billion and eight", ...

Crossrefs

Cf. A004740, A026081.

A026081 Integers in reverse alphabetical order in U.S. English.

Original entry on oeis.org

0, 2202202202202, 2202202202222, 2202202202223, 2202202202226
Offset: 1

Views

Author

Neil Fernandez

Keywords

Comments

This sequence is ill-defined from the 2nd term on. Proof: Assume that x is the term following the initial 0. Then the number x*10^(6n), for n sufficiently large, is spelled out: name(x) name(10^(6n)). This comes after name(x) in lexicographical order, and thus before x in this sequence. - M. F. Hasler, Nov 20 2009

Examples

			Zero, two trillion, two hundred and two billion, two hundred and two million, two hundred and two thousand, two hundred and two, ...

Crossrefs

Cf. A004740, A019440.
See A127352 for another version. - N. J. A. Sloane, Dec 05 2009

A045495 Smallest positive integer requiring at least n letters (not including hyphens) to be spelled out in English.

Original entry on oeis.org

1, 1, 1, 3, 3, 11, 13, 13, 17, 23, 23, 73, 101, 101, 101, 101, 103, 103, 111, 113, 113, 117, 123, 123, 173, 323, 373, 1103, 1103, 1111, 1113, 1113, 1117, 1123, 1123, 1173, 1323, 1373, 3323, 3373, 11373, 13323, 13373, 17373, 23323, 23373, 73373, 101123
Offset: 1

Views

Author

Brian Galebach

Keywords

Comments

Assumes British definition of billion trillion. Also assumes 'and' is used in numbers such as 'one hundred and one'.

Crossrefs

Cf. A000916, A001166, A014388, A045494, A045495, A167509.

Extensions

Added "at least" in definition, and a cross-reference M. F. Hasler, Nov 18 2009
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Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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