OFFSET
1,1
REFERENCES
GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See page 70.
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
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