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A076586 Total number of right truncatable primes in base n. 15
0, 4, 7, 14, 36, 19, 68, 68, 83, 89, 179, 176, 439, 373, 414, 473, 839, 1010, 1577, 2271, 2848, 1762, 3376, 5913, 6795, 6352, 10319, 5866, 14639, 13303, 19439, 29982, 38956, 39323, 58857, 41646, 68371, 80754, 128859, 81453, 175734, 161438, 228543, 396274, 538797 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,2
LINKS
Seth A. Troisi, Table of n, a(n) for n = 2..100 (terms n=2..53 from Martin Renner)
I. O. Angell and H. J. Godwin, On Truncatable Primes, Math. Comput. 31, 265-267, 1977.
PROG
(Python)
from sympy import isprime, primerange
from sympy.ntheory.digits import digits
def fromdigits(digs, base):
return sum(d*base**i for i, d in enumerate(digs))
def a(n):
prime_lists, an = [(p, ) for p in primerange(1, n)], 0
digits = 1
while len(prime_lists) > 0:
an += len(prime_lists)
candidates = set((d, )+p for p in prime_lists for d in range(1, n))
prime_lists = [c for c in candidates if isprime(fromdigits(c, n))]
digits += 1
return an
print([a(n) for n in range(2, 27)]) # Michael S. Branicky, May 03 2022
CROSSREFS
Sequence in context: A199628 A049945 A234576 * A240266 A064961 A137053
KEYWORD
nonn,base
AUTHOR
Martin Renner, Oct 20 2002, Sep 24 2007
STATUS
approved

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Last modified March 29 11:45 EDT 2024. Contains 371278 sequences. (Running on oeis4.)