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.
E.g., from the sequence of the valid primes (A072686) there are three prime-length primes between 1 and 10: 2,3,7; therefore a(1)=3.
23 ("twentythree", 11 letters) and 109 ("one hundred and nine", 17 letters) are counted.
from num2words import num2words
from sympy import isprime, primerange
def n2w(n):
return num2words(n).replace(chr(44), "").replace(" ", "").replace("-", "")
def a(n): return sum(isprime(len(n2w(p))) for p in primerange(2, 10**n))
print([a(n) for n in range(1, 7)]) # Michael S. Branicky, Mar 08 2021
e.g 137 -> CIENTOTREINTAYSIETE -> 19 letters and 19 is prime.
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