A244267 a(n) = the frequency of the most common 2-digit ending of a prime < 10^n.

1, 6, 35, 250, 1986, 16716, 144183, 1271765, 11378311, 102956670, 940224567, 8651691637, 80123673992

Offset: 2

Author

Derek Orr, Jun 24 2014

Keywords

• nonn
• base
• more
• hard

Examples

			Of the primes up to and including the last of the 3-digit primes, the most common 2-digit ending occurs 6 times. Thus a(3) = 6.
		

Crossrefs

Cf. A244192.

Programs

Python

import sympy
from sympy import isprime
def prend1(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)
  return max(newlst)
n = 3
while n < 10:
  print(prend1(2,n),end=', ')
  n += 1

Extensions

a(9)-a(12) from Hiroaki Yamanouchi, Aug 26 2014

Example corrected by Harvey P. Dale, Sep 27 2018

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