A278102 a(n) is the largest j such that A278101(n,k) strictly decreases for k=1..j.

1, 2, 3, 2, 3, 4, 2, 4, 2, 3, 2, 3, 4, 2, 4, 2, 3, 2, 3, 4, 2, 5, 6, 5, 2, 2, 3, 2, 4, 4, 4, 2, 2, 3, 2, 3, 4, 4, 5, 2, 2, 2, 3, 5, 3, 5, 2, 2, 2, 3, 5, 2, 4, 4, 4, 2, 3, 4, 2, 4, 5, 4, 2, 3, 2, 2, 4, 5, 4, 3, 3, 2, 2, 3, 5, 4, 5, 2, 2, 2, 3, 2, 3, 4, 2, 2, 2, 3, 2, 3, 4, 6, 5, 2, 3, 2, 2, 4, 6, 6, 2, 3, 2

Offset

1,2

Links

Jason Kimberley, Table of n, a(n) for n = 1..10000

Mathematica

Map[Length@ TakeWhile[FoldList[Function[s, Boole[s < 0] #2][#2 - #1] &, #], # > 0 &] &, #] &@ Map[DeleteCases[#, 0] &, Table[Boole[SquareFreeQ@ k] k Floor[n/Sqrt@ k]^2, {n, 23}, {k, n^2}] ] // Flatten (* Michael De Vlieger, Nov 24 2016 *)

Prog

(Magma)
A277647:=func<n, k|Isqrt(n^2 div k)>;
A278101_row:=func<n|[a^2*k where a is A277647(n, k):k in[1..n^2]|IsSquarefree(k)]>;
A278102:=func<n|(exists(j){j:j in[1..#row-1]|row[j]le row[j+1]}select j else #row) where row is A278101_row(n) >;
[A278102(n):n in[1..103]];

Crossrefs

This is the row length sequence for triangles A278103 and A278104.

A278106 lists first occurrences in this sequence.

Sequence in context: A076050 A130799 A243519 * A339500 A106383 A175794

Adjacent sequences: A278099 A278100 A278101 * A278103 A278104 A278105

Keyword

nonn,easy

Author

Jason Kimberley, Nov 15 2016

Status

approved