A049528 Number of letters in n-th prime (in English).

3, 5, 4, 5, 6, 8, 9, 8, 11, 10, 9, 11, 8, 10, 10, 10, 9, 8, 10, 10, 12, 11, 11, 10, 11, 13, 15, 15, 14, 18, 21, 19, 21, 20, 19, 18, 20, 20, 20, 22, 21, 19, 19, 21, 21, 20, 16, 21, 21, 20, 21, 20, 18, 18, 20, 20, 19, 20, 22, 19, 21, 21, 17, 18, 20, 21, 21, 23

Offset

1,1

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000

Formula

a(n) = A005589(A000040(n)) or a(n) = A052360(A000040(n)) depending on whether hyphens and spaces are excluded or included. - Jonathan Vos Post, Oct 19 2007

a(n) = A005589(A000040(n)) since it does not count spaces or hyphens. - Michael S. Branicky, Jul 12 2022

Example

a(13) = 8 because 'forty-one' contains 8 letters (not counting the hyphen).

Prog

(Python)
from sympy import nextprime
from itertools import count, islice
from num2words import num2words as n2w
def f(n): return sum(1 for c in n2w(n).replace(" and", "") if c.isalpha())
def agen(p=2):
    while True: yield f(p); p = nextprime(p)
print(list(islice(agen(), 68))) # Michael S. Branicky, Jul 12 2022

Crossrefs

Cf. A000040, A005589, A052360.

Sequence in context: A077861 A272647 A076308 * A206035 A200100 A057759

Adjacent sequences: A049525 A049526 A049527 * A049529 A049530 A049531

Keyword

easy,nice,nonn,word

Author

G. L. Honaker, Jr.

Extensions

a(66) and beyond from Michael S. Branicky, Jul 12 2022

Status

approved