cp's OEIS Frontend

A378625 The first subsequence starting at the first digit after the decimal point in the decimal expansion of Pi that is divisible by n.

%I A378625 #29 Dec 12 2024 15:38:08
%S A378625 1,14,141,141592,1415,141592653589793238,14,141592,141592653,
%T A378625 14159265358979323846264338327950,141592,
%U A378625 1415926535897932384626433832795028,14159265358979,14,14159265,1415926535897932384,141592653589793,141592653589793238,141592653589793238462
%N A378625 The first subsequence starting at the first digit after the decimal point in the decimal expansion of Pi that is divisible by n.
%C A378625 For every positive integer n there exists a contiguous subsequence of the decimal expansion of Pi that is divisible by n (conjectured).
%F A378625 a(n) = n * A088143(n). - _Alois P. Heinz_, Dec 05 2024
%e A378625 a(3) = 141 is the first integer in the sequence that is divisible by 3.
%e A378625 a(6) = 141592653589793238 is the first integer in the sequence that is divisibe by 6.
%o A378625 (Python)
%o A378625 from mpmath import mp
%o A378625 mp.dps = 1000000
%o A378625 pi_digits = str(mp.pi)[2:]
%o A378625 def first_divisible(n):
%o A378625     current_number = 0
%o A378625     for digit in pi_digits:
%o A378625         current_number = current_number * 10 + int(digit)
%o A378625         if current_number % n == 0:
%o A378625             return current_number
%o A378625     return None
%o A378625 results = [first_divisible(n) for n in range(1, 21)]
%o A378625 print(results)
%Y A378625 Cf. A000796, A088143.
%Y A378625 Cf. A014777 (if start can move).
%K A378625 nonn,base
%O A378625 1,2
%A A378625 _Simon R Blow_, Dec 02 2024