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 12 results. Next

A164791 a(n) is the smallest nonnegative number whose American English name has the letter "n" in the n-th position.

Original entry on oeis.org

9, 1, 9, 20, 7, 11, 15, 13, 17, 47, 27, 77, 109, 120, 107, 111, 115, 113, 117, 147, 127, 177, 327, 377, 1120, 1107, 1111, 1115, 1113, 1117, 1147, 1127, 1177, 1327, 1377, 3327, 3377, 11377, 13327, 13377, 17377, 23327, 23377, 73377, 101377, 103327, 103377
Offset: 1

Views

Author

Claudio Meller, Aug 26 2009

Keywords

Examples

			a(1)=9 ("Nine"), a(2)=1 ("oNe"), a(3)=9 ("niNe"), a(4)=20 ("tweNty").

References

  • GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See page 70.

Crossrefs

Cf. A164789 ("o"), A164790 ("e"), A164792 ("t"), A164793 ("i"), A164794 ("f"), A164795 ("h"), A164796 ("r"), A164797 ("u").

Programs

  • Python
    from num2words import num2words
from itertools import count, islice
def n2w(n):
  return "".join(c for c in num2words(n).replace(" and", "") if c.isalpha())
def a(n):
    return next(i for i in count(0) if len(w:=n2w(i))>=n and w[n-1]=="n")
print([a(n) for n in range(1, 41)]) # Michael S. Branicky, Apr 21 2023
  • Python
    # faster for initial segment of sequence; uses n2w, imports above
def agen(): # generator of terms
    adict, n = dict(), 1
    for i in count(0):
        w = n2w(i)
        if "n" in w:
            locs = [i+1 for i, c in enumerate(w) if w[i] == "n"]
            for v in locs:
                if v not in adict: adict[v] = i
        while n in adict: yield adict[n]; n += 1
print(list(islice(agen(), 50))) # Michael S. Branicky, Apr 21 2023

Extensions

a(25) and beyond from Michael S. Branicky, Mar 25 2021
Definition clarified by N. J. A. Sloane, Apr 20 2023. We also need a British English analog of this, just as A362121 is an analog of A164790 (a(13) will be different).

A164789 a(n) is the smallest number which has in its English name the letter "o" in the n-th position, or -1 if no such number exists.

Original entry on oeis.org

1, 4, 2, 0, 4000000000000000000000000000, 41, 21, 24, 22, 72, 101, 104, 102, 304, 302, 141, 121, 124, 122, 172, 322, 372, 1104, 1102, 1304, 1302, 1141, 1121, 1124, 1122, 1172, 1322, 1372, 3322, 3372, 11372, 13322, 13372, 17372, 23322, 23372, 73372, 101372, 103322, 103372
Offset: 1

Views

Author

Claudio Meller, Aug 26 2009

Keywords

Examples

			a(1)=1 ("One"), a(2)=4 ("fOur"), a(3)=2 ("twO"), a(4)=0 ("zerO"), a(5)=4*10^27 ("fourOctillion").

Crossrefs

Cf. A164790 ("e"), A164791 ("n"), A164792 ("t"), A164793 ("i").
Cf. A164794 ("f"), A164795 ("h"), A164796 ("r"), A164797 ("u").

Extensions

a(5) corrected and a(23) and beyond from Michael S. Branicky, Mar 25 2021

A164792 a(n) is the smallest number whose English name has the letter "t" in the n-th position, or -1 if no such number exists.

Original entry on oeis.org

2, -1, -1, 15, 8, 17, 22, 72, 13000, 48, 28, 78, 302, 115, 108, 117, 122, 172, 322, 148, 128, 178, 328, 378, 1115, 1108, 1117, 1122, 1172, 1322, 1148, 1128, 1178, 1328, 1378, 3328, 3378, 11378, 13328, 13378, 17378, 23328, 23378, 73378, 101378, 103328, 103378
Offset: 1

Views

Author

Claudio Meller, Aug 26 2009

Keywords

Examples

			a(1)=2 ("Two"), a(4)=15 ("fifTeen"), a(9)=13000 ("thirteenThousand"), a(13)=302 ("threehundredTwo").

Crossrefs

Cf. A164789 ("o"), A164790 ("e"), A164791 ("n"), A164793 ("i").
Cf. A164794 ("f"), A164795 ("h"), A164796 ("r"), A164797 ("u").

Extensions

a(9) corrected, and a(25) and beyond from Michael S. Branicky, Feb 02 2021

A164793 a(n) is the smallest number whose English name has the letter "i" in the n-th position, or -1 if no such number exists.

Original entry on oeis.org

-1, 5, 13, -1, 1000000, 4000000, 45, 25, 75, 13000000, 17000000, 105, 113, 305, 313, 3013, 145, 125, 175, 325, 375, 3075, 1105, 1113, 1305, 1313, 3305, 1145, 1125, 1175, 1325, 1375, 3325, 3375, 11375, 13325, 13375, 17375, 23325, 23375, 73375, 101375, 103325
Offset: 1

Views

Author

Claudio Meller, Aug 26 2009

Keywords

Comments

Original definition used "-2 for infinite".

Examples

			a(2)=5 ("fIve"), a(3)=13 ("thIrteen"), a(5)=10^6 ("onemIllion").

Crossrefs

Cf. A164789 ("o"), A164790 ("e"), A164791 ("n"), A164792 ("t").
Cf. A164794 ("f"), A164795 ("h"), A164796 ("r"), A164797 ("u").

Extensions

a(11) and beyond from Michael S. Branicky, Feb 02 2021
Name changed to remove "-2" (see Comments), and a(1) and a(4) changed from -2 to -1 by Jon E. Schoenfield, Feb 02 2021

A164794 a(n) is the smallest number whose English name has the letter "f" in the n-th position, or -1 if no such number exists.

Original entry on oeis.org

4, -1, 15, -1, -1, 44, 24, 74, -1, -1, 104, 404, 115, 415, 315, 144, 124, 174, 324, 374, 3074, 1104, 1404, 1115, 1415, 1315, 1144, 1124, 1174, 1324, 1374, 3324, 3374, 11374, 13324, 13374, 17374, 23324, 23374, 73374, 101374, 103324, 103374, 111374, 113324
Offset: 1

Views

Author

Claudio Meller, Aug 26 2009

Keywords

Examples

			a(1)=4 ("Four"), a(3)=15 ("fiFteen"), a(11)=104 ("onehundredFour").

Crossrefs

Cf. A164789 ("o"), A164790 ("e"), A164791 ("n"), A164792 ("t").
Cf. A164793 ("i"), A164795 ("h"), A164796 ("r"), A164797 ("u").

Extensions

a(21) and beyond from Michael S. Branicky, Feb 02 2021

A164795 a(n) is the smallest number whose English name has the letter "h" in the n-th position, or -1 if no such number exists.

Original entry on oeis.org

-1, 3, -1, 8, 400, 300, 43, 23, 48, 28, 78, 103, 403, 108, 408, 308, 143, 123, 148, 128, 178, 328, 378, 1403, 1108, 1408, 1308, 1143, 1123, 1148, 1128, 1178, 1328, 1378, 3328, 3378, 11378, 13328, 13378, 17378, 23328, 23378, 73378, 101378, 103328, 103378
Offset: 1

Views

Author

Claudio Meller, Aug 26 2009

Keywords

Examples

			a(2)=3 ("tHree"), a(4)=8 ("eigHt"), a(12)=103 ("onehundredtHree").

Crossrefs

Cf. A164789 ("o"), A164790 ("e"), A164791 ("n"), A164792 ("t").
Cf. A164793 ("i"), A164794 ("f"), A164796 ("r"), A164797 ("u").

Extensions

a(24) and beyond from Michael S. Branicky, Feb 02 2021

A164796 a(n) is the smallest number whose English name has the letter "r" in the n-th position, or -1 if no such number exists.

Original entry on oeis.org

-1, -1, 0, 4, 1000000000000, 4000000000000, 3000000000000, 43, 23, 24, 74, 24000000000000, 103, 104, 303, 304, 3004, 143, 123, 124, 174, 324, 374, 1103, 1104, 1303, 1304, 3303, 1143, 1123, 1124, 1174, 1324, 1374, 3324, 3374, 11374, 13324, 13374, 17374, 23324
Offset: 1

Views

Author

Claudio Meller, Aug 26 2009

Keywords

Examples

			a(3)=0 ("zeRo"), a(4)=4 ("fouR"), a(5)=1000000000000 ("onetRillion"), a(13)=103 ("onehundredthRee").

Crossrefs

Cf. A164789 ("o"), A164790 ("e"), A164791 ("n"), A164792 ("t").
Cf. A164793 ("i"), A164794 ("f"), A164795 ("h"), A164797 ("u").

Extensions

a(24) and beyond from Michael S. Branicky, Feb 02 2021

A164797 a(n) is the smallest number whose English name has the letter "u" in the n-th position, or -1 if no such number exists.

Original entry on oeis.org

-1, -1, 4, 1000000000000000000000000000000000000, 100, 400, 300, 44, 24, 74, 15000, 13000, 104, 404, 304, 4004, 1100, 144, 124, 174, 324, 374, 3024, 3074, 1104, 1404, 3404, 3304, 1144, 1124, 1174, 1324, 1374, 3324, 3374, 11374, 13324, 13374, 17374, 23324, 23374
Offset: 1

Views

Author

Claudio Meller, Aug 26 2009

Keywords

Examples

			a(3)=4 ("foUr"), a(5)=100 ("onehUndred"), a(4)=10^36 ("oneUndecillion").

Links

Crossrefs

Cf. A164789 ("o"), A164790 ("e"), A164791 ("n"), A164792 ("t").
Cf. A164793 ("i"), A164794 ("f"), A164795 ("h"), A164796 ("r").

Extensions

a(4) corrected, and a(27) and beyond from Michael S. Branicky, Feb 02 2021

A362120 a(n) is the smallest positive number whose American English name has the letter "e" in the n-th position.

Original entry on oeis.org

8, 7, 1, 3, 3, 12, 13, 17, 21, 23, 23, 73, 101, 103, 103, 112, 113, 117, 121, 123, 123, 173, 323, 373, 1103, 1103, 1112, 1113, 1117, 1121, 1123, 1123, 1173, 1323, 1373, 3323, 3373, 11373, 13323, 13373, 17373, 23323, 23373, 73373, 101373, 103323, 103373, 111373
Offset: 1

Views

Author

N. J. A. Sloane, Apr 20 2023

Keywords

References

  • GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See page 70.

Crossrefs

See A164790, A362121, A362122 for other versions.

Programs

  • Python
    from itertools import count
from num2words import num2words
def A362120(n): return next(filter(lambda k:len(s:=num2words(k).replace('-','').replace(',','').replace(' and ','').replace(' ',''))>=n and s[n-1]=='e',count(1))) # Chai Wah Wu, Apr 21 2023

A362121 a(n) is the smallest nonnegative number whose British English name has the letter "e" in the n-th position.

Original entry on oeis.org

8, 0, 1, 3, 3, 12, 13, 17, 21, 23, 23, 73, 1700, 108, 107, 101, 103, 103, 112, 113, 117, 121, 123, 123, 173, 323, 373, 1103, 1103, 1112, 1113, 1117, 1121, 1123, 1123, 1173, 1323, 1373, 3323, 3373, 11373, 13323, 13373, 17373, 23323, 23373, 73373, 101123, 101173
Offset: 1

Views

Author

N. J. A. Sloane, Apr 20 2023

Keywords

References

  • GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See page 70.

Crossrefs

See A164790, A362120, and A362122 for other versions.

Programs

  • Python
    from num2words import num2words
from itertools import count, islice
def n2w(n):
    return "".join(c for c in num2words(n, lang='en_GB') if c.isalpha())
def A362121(n, t="e", i0=0): # t is target letter, i0 is start
    return next(i for i in count(i0) if len(w:=n2w(i))>=n and w[n-1]==t)
print([A362121(n) for n in range(1, 31)]) # Michael S. Branicky, Apr 21 2023
  • Python
    # faster for initial segment of sequence; uses n2w, imports above
def A362121gen(t="e", i0=0, offset=1): # generator of terms w
    adict, n = dict(), offset
    for i in count(i0):
        w = n2w(i)
        if t in w:
            locs = [i+1 for i, c in enumerate(w) if w[i] == t]
            for v in locs:
                if v not in adict: adict[v] = i
        while n in adict: yield adict[n]; n += 1
print(list(islice(A362121gen(), 50))) # Michael S. Branicky, Apr 21 2023

Extensions

a(14) and beyond from Michael S. Branicky, Apr 21 2023
Showing 1-10 of 12 results. Next

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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