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%I #28 Oct 23 2018 03:21:38
%S 0,0,0,97,71,91,77,61,47,47,19,27,37
%N a(n) = most common 2-digit ending for a prime < 10^n, or 0 if there is a tie.
%C a(3) = 0 because '83' and '57' both appear 6 times in the endings of primes < 1000.
%C a(4) = 0 because '19' and '23' both appear 35 times in the endings of primes < 10000.
%e For all primes < 100000 (10^5), the most common 2-digit ending is 97. Thus a(5) = 97.
%o (Python)
%o import sympy
%o from sympy import isprime
%o def prend(d,n):
%o ..lst = []
%o ..for k in range(10**n):
%o ....if isprime(k):
%o ......lst.append((k%10**d))
%o ..new = 0
%o ..newlst = []
%o ..for i in range(10**(d-1),10**d):
%o ....new = lst.count(i)
%o ....newlst.append(new)
%o ..newlst1 = newlst.copy()
%o ..a = max(newlst1)
%o ..newlst1[newlst1.index(a)] = 0
%o ..b = max(newlst1)
%o ..if a == b:
%o ....return 0
%o ..else:
%o ....return newlst.index(max(a,b)) + 10**(d-1)
%o n = 3
%o while n < 10:
%o ..print(prend(2,n),end=', ')
%o ..n += 1
%Y Cf. A244191, A244267.
%K nonn,base,hard,more
%O 2,4
%A _Derek Orr_, Jun 22 2014
%E a(9)-a(12) from _Hiroaki Yamanouchi_, Jul 11 2014
%E a(13)-a(14) from _Giovanni Resta_, Oct 23 2018
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