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 A244190 a(n) = most common 2-digit ending for a prime with n digits, or 0 if there is a tie. 2
 0, 57, 0, 97, 71, 93, 59, 73, 47, 51, 19, 27 (list; graph; refs; listen; history; text; internal format)
 OFFSET 2,2 COMMENTS 21 and 23 are tied with 4-digit primes so a(4) = 0. LINKS Table of n, a(n) for n=2..13. EXAMPLE Of the primes with 3 digits, the most common 2 digit ending is 57. Thus a(3) = 57. PROG (Python) import sympy from sympy import isprime def end(d, n): ..lst = [] ..for k in range(10**(d-1), 10**d): ....num = '' ....count = 0 ....for i in range(10**(n-d-1), 10**(n-d)): ......if isprime(int(str(i)+str(k))): ........count += 1 ....lst.append(count) ..a = max(lst) ..lst[lst.index(a)] = 0 ..b = max(lst) ..if a == b: ....return 0 ..else: ....return max(a, b) + 10**(d-1) n = 3 while n < 10: ..print(end(2, n), end=', ') ..n += 1 CROSSREFS Cf. A244189. Sequence in context: A101355 A285179 A307938 * A013682 A278068 A126828 Adjacent sequences: A244187 A244188 A244189 * A244191 A244192 A244193 KEYWORD nonn,base,hard,more AUTHOR Derek Orr, Jun 22 2014 EXTENSIONS a(9) from Tom Edgar, Jun 24 2014 a(10)-a(12) from Hiroaki Yamanouchi, Jul 11 2014 a(13) from Marek Hubal, Mar 04 2019 STATUS approved

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Last modified August 15 12:24 EDT 2024. Contains 375173 sequences. (Running on oeis4.)