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%I #12 Aug 17 2024 12:20:36
%S 1,2,2,3,2,2,3,3,4,3,3,4,5,4,5,6,3,7,4,5,8,6,7,3,3,3,4,4,3,4,4,4,5,3,
%T 4,5,6,5,7,4,4,6,5,5,8,4,5,6,6,4,4,4,5,4,5,6,7,5,4,5,4,5,5,8,5,4,6,7,
%U 7,8,9,10,9,10,11,11,12,12,13,13,8,14,9,15
%N a(n) is the maximum number of points from the set {(k, prime(k)), k = 1..n} belonging to a straight line passing through the point (n, prime(n)) (where prime(k) denotes the k-th prime number).
%C Is this sequence unbounded?
%H Rémy Sigrist, <a href="/A375422/b375422.txt">Table of n, a(n) for n = 1..10000</a>
%H Rémy Sigrist, <a href="/A375422/a375422.txt">C++ program</a>
%H Rémy Sigrist, <a href="/A375422/a375422.gp.txt">PARI program</a>
%e The first terms, alongside an appropriate set of points, are:
%e n a(n) Points
%e -- ---- --------------------------------------------------
%e 1 1 (1,2)
%e 2 2 (1,2), (2,3)
%e 3 2 (1,2), (3,5)
%e 4 3 (2,3), (3,5), (4,7)
%e 5 2 (1,2), (5,11)
%e 6 2 (1,2), (6,13)
%e 7 3 (3,5), (5,11), (7,17)
%e 8 3 (2,3), (5,11), (8,19)
%e 9 4 (3,5), (5,11), (7,17), (9,23)
%e 10 3 (6,13), (7,17), (10,29)
%e 11 3 (8,19), (9,23), (11,31)
%e 12 4 (6,13), (7,17), (10,29), (12,37)
%e 13 5 (6,13), (7,17), (10,29), (12,37), (13,41)
%e 14 4 (8,19), (9,23), (11,31), (14,43)
%e 15 5 (8,19), (9,23), (11,31), (14,43), (15,47)
%e 16 6 (6,13), (7,17), (10,29), (12,37), (13,41), (16,53)
%o (C++) // See Links section.
%o (PARI) \\ See Links section.
%Y Cf. A334046, A375386.
%K nonn
%O 1,2
%A _Rémy Sigrist_, Aug 14 2024