A214856 Number of triangular numbers in interval ](n-1)^2, n^2] for n>0, a(0)=1.

1, 1, 1, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 1, 2, 1

Offset

0,5

Links

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

Example

10, 15 are in interval ]9, 16] , a(4) = 2.

Prog

(PARI) a(n) = if (n, sum(i=(n-1)^2+1, n^2, ispolygonal(i, 3)), 1); \\ Michel Marcus, Nov 12 2022

Crossrefs

Cf. A214848

Sequence in context: A105690 A214364 A175922 * A006337 A214848 A006338

Adjacent sequences: A214853 A214854 A214855 * A214857 A214858 A214859

Keyword

nonn,easy

Author

Philippe Deléham, Mar 08 2013

Status

approved