A083403 Write the numbers 1, 2, ... in a triangle with n terms in the n-th row; a(n) = number of squarefree integers in n-th row.

1, 2, 2, 2, 4, 3, 3, 6, 6, 5, 7, 8, 8, 8, 10, 8, 10, 11, 12, 13, 15, 11, 14, 14, 16, 14, 15, 19, 19, 19, 18, 20, 19, 21, 21, 22, 24, 21, 24, 26, 22, 27, 26, 26, 27, 27, 29, 30, 30, 31, 32, 32, 33, 32, 34, 35, 35, 33, 36, 34, 36, 37, 40, 37, 42, 40, 41, 43, 42, 44, 40, 45, 44, 46

Offset

1,2

Links

Table of n, a(n) for n=1..74.

Example

Triangle begins
1 (1 squarefree)
2 3 (2 squarefree)
4 5 6 (2 squarefree)
7 8 9 10 (2 squarefree)
11 12 13 14 15 (4 squarefree)
16 17 18 19 20 21 (3 squarefree)

Prog

(PARI) {ts(m)=local(r, t); r=1; for(n=1, m, t=0; for(k=r, n+r-1, if(issquarefree(k), t++)); print1(t", "); r=n+r; ) }

Crossrefs

Cf. A066888, A005117.

Sequence in context: A347628 A338796 A085454 * A114091 A209580 A166008

Adjacent sequences: A083400 A083401 A083402 * A083404 A083405 A083406

Keyword

easy,nonn

Author

Jason Earls, Jun 07 2003

Status

approved