cp's OEIS Frontend

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

%I A244267 #19 May 22 2025 10:21:39
%S A244267 1,6,35,250,1986,16716,144183,1271765,11378311,102956670,940224567,
%T A244267 8651691637,80123673992
%N A244267 a(n) = the frequency of the most common 2-digit ending of a prime < 10^n.
%e A244267 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.
%o A244267 (Python)
%o A244267 import sympy
%o A244267 from sympy import isprime
%o A244267 def prend1(d,n):
%o A244267   lst = [ ]
%o A244267   for k in range(10**n):
%o A244267     if isprime(k):
%o A244267       lst.append((k%10**d))
%o A244267   new = 0
%o A244267   newlst = [ ]
%o A244267   for i in range(10**(d-1),10**d):
%o A244267     new = lst.count(i)
%o A244267     newlst.append(new)
%o A244267   return max(newlst)
%o A244267 n = 3
%o A244267 while n < 10:
%o A244267   print(prend1(2,n),end=', ')
%o A244267   n += 1
%Y A244267 Cf. A244192.
%K A244267 nonn,base,more,hard
%O A244267 2,2
%A A244267 _Derek Orr_, Jun 24 2014
%E A244267 a(9)-a(12) from _Hiroaki Yamanouchi_, Aug 26 2014
%E A244267 Example corrected by _Harvey P. Dale_, Sep 27 2018
%E A244267 a(13)-a(14) from _Giovanni Resta_, Oct 23 2018