A000861 -id:A000861 - cp's OEIS frontend

A247361 Interleave A000861\{0} and A247359: positive numbers with English name ending in a vowel resp. consonant.

1, 4, 2, 6, 3, 7, 5, 8, 9, 10, 12, 11, 21, 13, 22, 14, 23, 15, 25, 16, 29, 17, 31, 18, 32, 19, 33, 20, 35, 24, 39, 26, 41, 27, 42, 28, 43, 30, 45, 34, 49, 36, 51, 37, 52, 38, 53, 40, 55, 44, 59, 46, 61, 47, 62, 48, 63, 50, 65, 54, 69, 56, 71, 57, 72, 58, 73, 60, 75, 64, 79, 66, 81, 67, 82, 68, 83, 70, 85, 74, 89, 76, 91, 77, 92, 78, 93, 80, 95, 84, 99

Offset: 1

M. F. Hasler, Sep 14 2014

A permutation of the positive integers.

See A247362 for a variant defined on the nonnegative integers.

			Every other term is taken from the set A000861 \ {0} = {onE, twO, threE, fivE, ninE, twelvE, ...} resp. from A247359 = {fouR, siX, seveN, eighT, teN, eleveN, ...}

Cf. A000861, A247359, A247362.

a(2n)=A247362(2n-1), a(2n-1) = A247362(2n).

A247362 Interleave A000861 and A247359, numbers ending in a vowel resp. consonant in English.

Original entry on oeis.org

0, 4, 1, 6, 2, 7, 3, 8, 5, 10, 9, 11, 12, 13, 21, 14, 22, 15, 23, 16, 25, 17, 29, 18, 31, 19, 32, 20, 33, 24, 35, 26, 39, 27, 41, 28, 42, 30, 43, 34, 45, 36, 49, 37, 51, 38, 52, 40, 53, 44, 55, 46, 59, 47, 61, 48, 62, 50, 63, 54, 65, 56, 69, 57, 71, 58, 72

Offset: 0

M. F. Hasler, Sep 14 2014

A permutation of the nonnegative integers.

See A247361 for the analog permutation of the positive integers, starting with a(1)=1.

Cf. A152592, A059437.

A037196 Number of vowels in the American English name of n.

Original entry on oeis.org

2, 2, 1, 2, 2, 2, 1, 2, 2, 2, 1, 3, 2, 3, 4, 3, 3, 4, 4, 4, 1, 3, 2, 3, 3, 3, 2, 3, 3, 3, 1, 3, 2, 3, 3, 3, 2, 3, 3, 3, 1, 3, 2, 3, 3, 3, 2, 3, 3, 3, 1, 3, 2, 3, 3, 3, 2, 3, 3, 3, 1, 3, 2, 3, 3, 3, 2, 3, 3, 3, 2, 4, 3, 4, 4, 4, 3, 4, 4, 4, 2, 4, 3, 4, 4, 4, 3, 4, 4, 4, 2, 4, 3, 4, 4, 4, 3, 4, 4, 4, 4, 6, 5, 6, 6

Offset: 0

N. J. A. Sloane

"American English" means that there is no "and" in the names of numbers, cf. example. - M. F. Hasler, Aug 26 2020

			a(20) = 1 for "twEnty" with 1 vowel: 'y' does not count.
a(101) = 6 for "OnE hUndrEd OnE" with 6 vowels: no "and" as in the "British" variant "one hundred and one" which would have 7 vowels.

Cf. A005589, A052360 (number of letters in English name of numbers with/without spaces and dashes).

Sequences related to vowels: A102869, A158352, A158354 (smallest number with n [distinct] vowels in AE / BE), A158353, A158355 (ditto, increasing), A058179 (all 5 vowels), A058180 (ditto, exactly once), A000852, A000861 (start/end with vowel), A019270, A080518 (self-describing), A059437, A079741, A152592, A174879, A241858, A332068, A332069.

vowels=Vec("aeiou"); apply( {A037196(n)=#[c|c<-Vec(English(n)),setsearch(vowels,c)]}, [0..104]) \\ see A052360 for English(). - M. F. Hasler, Aug 26 2020

from num2words import num2words
def a(n): return sum(1 for c in num2words(n).replace(" and", "") if c in "aeiou")
print([a(n) for n in range(105)]) # Michael S. Branicky, Mar 23 2025

More terms from Larry Reeves (larryr(AT)acm.org), Sep 25 2000
Name edited and crossrefs added by M. F. Hasler, Aug 26 2020
a(19)=4 corrected by Sean A. Irvine, Dec 16 2020

A079741 Numbers ending with a vowel or the letter y in American English.

Original entry on oeis.org

0, 1, 2, 3, 5, 9, 12, 20, 21, 22, 23, 25, 29, 30, 31, 32, 33, 35, 39, 40, 41, 42, 43, 45, 49, 50, 51, 52, 53, 55, 59, 60, 61, 62, 63, 65, 69, 70, 71, 72, 73, 75, 79, 80, 81, 82, 83, 85, 89, 90, 91, 92, 93, 95, 99, 101, 102, 103, 105, 109, 112, 120, 121, 122, 123, 125, 129, 130

Offset: 1

Hollie L. Buchanan II, Feb 17 2003

Cf. A000861.

More terms from Robert G. Wilson v, Mar 13 2003

0 inserted by Sean A. Irvine, Aug 25 2025

A247359 Numbers whose English name ends in a consonant.

Original entry on oeis.org

4, 6, 7, 8, 10, 11, 13, 14, 15, 16, 17, 18, 19, 20, 24, 26, 27, 28, 30, 34, 36, 37, 38, 40, 44, 46, 47, 48, 50, 54, 56, 57, 58, 60, 64, 66, 67, 68, 70, 74, 76, 77, 78, 80, 84, 86, 87, 88, 90, 94, 96, 97, 98, 100, 104, 106, 107, 108, 110, 111, 113, 114, 115, 116, 117

Offset: 1

M. F. Hasler, Sep 14 2014

Complement of A000861.

Sequence A152592 is the characteristic function of this set, A059437 would yield a variant including multiples of 10: 20, 30, ..., 90, 120, 130, ...

Cf. A247359.

A098060 Numbers whose French names end in a vowel.

Original entry on oeis.org

0, 4, 11, 12, 13, 14, 15, 16, 24, 30, 34, 40, 44, 50, 54, 60, 64, 71, 72, 73, 74, 75, 76, 84, 91, 92, 93, 94, 95, 96, 104, 111, 112, 113, 114, 115, 116, 124, 130, 134, 140, 144, 150, 154, 160, 164, 171, 172, 173, 174, 175, 176, 184, 191, 192, 193, 194, 195, 196

Offset: 1

Axel Harvey, Oct 24 2004

Note that the sequence is for France. Different sequences would be obtained in Belgium and in Switzerland. - Michel Marcus, Aug 20 2013

			The sequence begins with 0 and 4 because 0,1,2,3,4... are: zero, un, deux, trois, quatre, ....
The French name of the first terms are: zerO, quatrE, onzE, douzE, treizE, quatorzE, quinzE, seizE, vingt-quatrE, trentE, ... soixantE, soixante-quatrE, soixante-et-onzE, ... The complement of this sequence lists: uN, deuX, troiS, cinQ, siX, sepT, huiT, neuF, diX, dix-sepT, dix-huiT, dix-neuF, vingT, vingt-et-uN, ..., soixante-diX, soixante-dix-sepT, ... - _M. F. Hasler_, Sep 15 2014

Cf. A000861, A079741, A247359, A247360.

A291663 Numbers beginning with a vowel in Danish.

Original entry on oeis.org

1, 8, 11, 18, 21, 28, 31, 38, 41, 48, 51, 58, 61, 68, 71, 78, 81, 88, 91, 98, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149

Offset: 1

Halfdan Skjerning, Aug 29 2017

The sequence of words is: en, otte, elleve, atten, enogtyve, otteogtyve, enogtredive, otteogtredive, enogfyrre, otteogfyrre, enoghalvtreds, otteoghalvtreds, enogtreds, otteogtreds, enoghalvfjerds, ...

Halfdan Skjerning, Table of n, a(n) for n = 1..150
Brady Haran and Tom Scott, 58 and other Confusing Numbers, Numberphile video (2015)
Wikipedia, List of numbers in various languages

Cf. A000861, A079741, A098060, A247751, A291621.

Select[Range@ 149, With[{d = IntegerDigits@ #}, MemberQ[{1, 8}, If[Length@ d == 2, First@ Reverse@ d, First@ d]]] &] (* Michael De Vlieger, Aug 30 2017 *)

All numbers beginning with '1' or '8', except for two-digit numbers that do not end in '1' or '8'.

A247360 Numbers with French name ending in a consonant.

Original entry on oeis.org

1, 2, 3, 5, 6, 7, 8, 9, 10, 17, 18, 19, 20, 21, 22, 23, 25, 26, 27, 28, 29, 31, 32, 33, 35, 36, 37, 38, 39, 41, 42, 43, 45, 46, 47, 48, 49, 51, 52, 53, 55, 56, 57, 58, 59, 61, 62, 63, 65, 66, 67, 68, 69, 70, 77, 78, 79, 80, 81, 82, 83, 85, 86, 87, 88, 89

Offset: 1

M. F. Hasler, Sep 14 2014

Complement of A098060.

			The French name of the first terms are: uN, deuX, troiS, cinQ, siX, sepT, huiT, neuF, diX, dix-sepT, dix-huiT, dix-neuF, vingT, vingt-et-uN, ..., soixante-diX, soixante-dix-sepT, ...
Numbers not included are: zerO, quatrE, onzE, douzE, treizE, quatorzE, quinzE, seizE, vingt-quatrE, trentE, ... soixantE, soixante-quatrE, soixante-et-onzE, ...

Cf. A247359, A000861 (English analog).

A291621 Numbers ending with a vowel in Danish.

Original entry on oeis.org

2, 3, 4, 8, 9, 10, 11, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 33, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 100, 102, 103, 104, 108, 109, 110, 111, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 200

Offset: 1

Halfdan Skjerning, Aug 28 2017

The sequence of words is: to, tre, fire, otte, ni, ti, elleve, tyve, enogtyve, toogtyve, treogtyve, ...
In Danish, when pronouncing a two-digit number, the last number is mentioned first; for example, '21' is "enogtyve" ["one-and-twenty"], and '121' is "ethundredeogenogtyve" ["one-hundred-and-one-and-twenty"].
All numbers ending with 02, 03, 04, 08, 09, 10, 3n, 4n, n00, or n000 will end in a vowel.
Please note that '100' can be both spelled and pronounced as "hundrede", "ethundrede", "hundred" and "ethundred"; similarly, '1000' can be spelled "tusinde", "ettusinde", "tusind" and "ettusind". The "et" in "ethundrede" is often omitted in daily speech.

Den Danske Ordbog, hundrede
Den Danske Ordbog, tusinde
Brady Haran and Tom Scott, 58 and other Confusing Numbers, Numberphile video (2015)
Wikipedia, List of numbers in various languages

Cf. A000861, A079741, A098060, A247751.

All numbers ending with 02, 03, 04, 08, 09, 10, 3n, 4n, n00, n000.

A332068 Numbers whose English name has at least two vowels and all the vowels are in alphabetical order.

Original entry on oeis.org

0, 3, 4, 7, 8, 11, 12, 17, 22, 23, 24, 26, 27, 28, 32, 34, 36, 42, 44, 52, 54, 56, 62, 64, 66, 70, 72, 73, 74, 76, 77, 78, 80, 82, 84, 86, 3000000, 3000002, 3000004, 3000040, 3000042, 3000044, 6000000, 6000002, 6000004, 6000040, 6000042, 6000044, 7000000, 7000002, 7000004

Offset: 1

M. F. Hasler, Aug 10 2020

Here (as in most OEIS sequences) vowel means one of the five letters A, E, I, O or U. (One could imagine variants that use Y, too.)
No number with "hUndrEd", "thoUsAnd", or "One / twO / foUr mIllioN" (or "fIvE, nInE"...) in it has the required property.
The vowels are counted with multiplicity: e.g., "thrEE" with two 'E's is listed.
The subsequence of numbers which have at least two distinct vowels in alphabetical order is 0, 4, 8, 22, 24, 26, 28, 32, 34, 44, 52, 54, 62, 64, 72, 74, 76, 78, 80, 82, 84, 86, 3000000, ...

			Numbers 0, 3, 4, ... have the required property, since their English names are "zErO", "thrEE", "fOUr", ...
Numbers 1, 2, 5, ... ("OnE", "twO", "fIvE", ...) don't have the property (vowels in incorrect order or less than two).

Cf. A052360.
A095947 \ {10} is the subset of numbers having only vowel E, and more than once.
Sequences related to vowels: A037196 (# vowels), A102869, A158352, A158354 (smallest number with n [distinct] vowels in AE / BE), A158353, A158355 (ditto, increasing), A058179 (all 5 vowels), A058180 (ditto, exactly once), A000852, A000861 (start/end with vowel), A019270, A080518 (self-describing), A059437, A079741, A152592, A174879, A241858.
See A332069 for numbers having all 5 vowels, in alphabetical order.

select( {is_A332068(n,v=Vec("aeiou"))=#(t=[c|c<-Vec(English(n)),setsearch(v,c)])>1&&t==vecsort(t)}, [0..999]) \\ See A052360 for English(). Insert "Set" after '#' to get the subset of numbers with > 1 distinct vowels.

cp's OEIS Frontend

A247361 Interleave A000861\{0} and A247359: positive numbers with English name ending in a vowel resp. consonant.

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A247362 Interleave A000861 and A247359, numbers ending in a vowel resp. consonant in English.

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A037196 Number of vowels in the American English name of n.

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A079741 Numbers ending with a vowel or the letter y in American English.

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A247359 Numbers whose English name ends in a consonant.

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A098060 Numbers whose French names end in a vowel.

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A291663 Numbers beginning with a vowel in Danish.

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Mathematica

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A247360 Numbers with French name ending in a consonant.

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A291621 Numbers ending with a vowel in Danish.

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A332068 Numbers whose English name has at least two vowels and all the vowels are in alphabetical order.

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PARI