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

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

1,1

References

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

Links

Table of n, a(n) for n=1..47.

Example

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

Prog

(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

Crossrefs

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

Sequence in context: A133919 A145078 A093644 * A107829 A062357 A348974

Adjacent sequences: A164788 A164789 A164790 * A164792 A164793 A164794

Keyword

nonn,word

Author

Claudio Meller, Aug 26 2009

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).

Status

approved