A244191 a(n) = most common final digit for a prime < 10^n, or 0 if there is a tie.

0, 3, 7, 3, 7, 3, 3, 7, 3, 3, 7, 7, 3, 3

Offset: 1

Author

Derek Orr, Jun 22 2014

Keywords

• nonn
• base
• hard
• more

Examples

			For all 25 primes < 100 (10^2), we see that the last digit that appears the most is 3. Thus a(2) = 3.
		

Links

• Index entries for sequences related to final digits of numbers

Crossrefs

Cf. A007652, A095178, A244192.

Programs

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 = 2
while n < 10:
  print(prend(1,n),end=', ')
  n += 1

Extensions

a(9)-a(14) from Hiroaki Yamanouchi, Sep 27 2014