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A244192 a(n) = most common 2-digit ending for a prime < 10^n, or 0 if there is a tie. 2
0, 0, 0, 97, 71, 91, 77, 61, 47, 47, 19, 27, 37 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,4

COMMENTS

a(3) = 0 because '83' and '57' both appear 6 times in the endings of primes < 1000.

a(4) = 0 because '19' and '23' both appear 35 times in the endings of primes < 10000.

LINKS

Table of n, a(n) for n=2..14.

EXAMPLE

For all primes < 100000 (10^5), the most common 2-digit ending is 97. Thus a(5) = 97.

PROG

(Python)

import sympy

from sympy import isprime

def prend(d, n):

..lst = []

..for k in range(10**n):

....if isprime(k):

......lst.append((k%10**d))

..new = 0

..newlst = []

..for i in range(10**(d-1), 10**d):

....new = lst.count(i)

....newlst.append(new)

..newlst1 = newlst.copy()

..a = max(newlst1)

..newlst1[newlst1.index(a)] = 0

..b = max(newlst1)

..if a == b:

....return 0

..else:

....return newlst.index(max(a, b)) + 10**(d-1)

n = 3

while n < 10:

..print(prend(2, n), end=', ')

..n += 1

CROSSREFS

Cf. A244191, A244267.

Sequence in context: A033417 A182690 A088866 * A075478 A126146 A112667

Adjacent sequences:  A244189 A244190 A244191 * A244193 A244194 A244195

KEYWORD

nonn,base,hard,more

AUTHOR

Derek Orr, Jun 22 2014

EXTENSIONS

a(9)-a(12) from Hiroaki Yamanouchi, Jul 11 2014

a(13)-a(14) from Giovanni Resta, Oct 23 2018

STATUS

approved

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Last modified September 29 22:48 EDT 2022. Contains 357092 sequences. (Running on oeis4.)