A233795 Number of triangular numbers between triangular(n) and n^2.

0, 0, 0, 0, 1, 1, 1, 2, 2, 3, 3, 4, 4, 4, 5, 5, 6, 6, 6, 7, 7, 8, 8, 9, 9, 9, 10, 10, 11, 11, 11, 12, 12, 13, 13, 13, 14, 14, 15, 15, 16, 16, 16, 17, 17, 18, 18, 18, 19, 19, 20, 20, 21, 21, 21, 22, 22, 23, 23, 23, 24, 24, 25, 25, 26, 26, 26, 27, 27, 28, 28, 28, 29, 29

Offset

0,8

Comments

Number of triangular numbers t such that n*(n+1)/2 < t < n^2.

Links

Table of n, a(n) for n=0..73.

Mathematica

nn = 110; tri = Table[n (n + 1)/2, {n, nn}]; mx = Floor[Sqrt[tri[[-1]]]]; Join[{0}, Table[Length[Intersection[tri, Range[tri[[n]] + 1, n^2 - 1]]], {n, mx}]] (* T. D. Noe, Dec 20 2013 *)

Crossrefs

Cf. A000217, A000290, A233473.

Cf. A022846 (number of triangular numbers less than n^2).

Sequence in context: A225545 A088462 A189574 * A093337 A254528 A176044

Adjacent sequences: A233792 A233793 A233794 * A233796 A233797 A233798

Keyword

nonn

Author

Alex Ratushnyak, Dec 16 2013

Status

approved