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A085761
Number of triangular numbers between n and 2n (inclusive).
1
1, 1, 2, 1, 2, 2, 1, 2, 2, 2, 2, 2, 2, 3, 3, 2, 2, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 4, 3, 3, 3, 3, 4, 4, 4, 4, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 7
OFFSET
1,3
MATHEMATICA
With[{trnos=Accumulate[Range[100]]}, Table[Count[trnos, _?(n<=#<=2n&)], {n, 110}]] (* Harvey P. Dale, Jul 23 2013 *)
CROSSREFS
Sequence in context: A118916 A107800 A245760 * A352884 A102382 A024890
KEYWORD
easy,nonn
AUTHOR
Amarnath Murthy, Jason Earls, Jul 22 2003
STATUS
approved