A395161 k is a term if and only if, in the process described at A394915, there are no new point-like intersections after step k.

1, 3, 12, 14, 16, 19, 22, 37, 40, 47, 54, 55, 56, 71, 73, 74, 76, 84, 86, 96, 102, 103, 105, 107, 108, 110, 111, 118, 119, 123, 129, 130, 133, 161, 165, 174, 179, 184, 185, 188, 195, 200, 213, 219, 240, 254, 255, 272, 273, 292, 299, 330, 334, 340, 354, 355, 356, 358, 359, 370, 386, 388

Offset

1,2

Comments

In other words, k is a term iff the line drawn at step k coincides with a line drawn at an earlier step.

Links

Paolo Xausa, Table of n, a(n) for n = 1..1000

Mathematica

A395161list[upto_] := With[{lines = MapIndexed[{#[[2]] - #[[1]], #[[1]] - (#[[2]] - #[[1]])*#2[[1]]} &, Partition[Prime[Range[upto+1]], 2, 1]]}, Table[If[k == 1 || MemberQ[lines[[;; k-1]], lines[[k]]], k, Nothing], {k, upto}]];
A395161list[500]

Crossrefs

Cf. A394915.

Positions of zeros in A394225.

Sequence in context: A341799 A089919 A222711 * A176796 A242130 A286386

Adjacent sequences: A395154 A395156 A395160 * A395162 A395163 A395164

Keyword

nonn

Author

Paolo Xausa, Apr 14 2026

Status

approved