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A096180 Triangle read by rows: fraction of integers having k of the first n positive integers as divisors is T(n,k)/A003418(n). 5
1, 1, 1, 2, 3, 1, 4, 4, 3, 1, 16, 20, 16, 7, 1, 16, 20, 12, 6, 5, 1, 96, 136, 92, 48, 36, 11, 1, 192, 272, 136, 124, 66, 38, 11, 1, 576, 720, 464, 360, 206, 122, 58, 13, 1, 576, 720, 392, 384, 188, 154, 70, 26, 9, 1, 5760, 7776, 4640, 4232, 2264, 1728, 854, 330, 116, 19 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,4

COMMENTS

Sum of entries in n-th row is A003418(n), the least common multiple of integers 1 to n.

LINKS

Table of n, a(n) for n=1..65.

EXAMPLE

Triangle begins:

1

1 1

2 3 1

4 4 3 1

16 20 16 7 1

16 20 12 6 5 1

PROG

(PARI) lcmn(n) = lcm(vector(n, k, k));

rowd(n) = {v = vector(n); for (k=1, lcmn(n), d = divisors(k); v[sum(j=1, #d, d[j]<=n)]++; ); v; } \\ Michel Marcus, Apr 29 2017

CROSSREFS

Cf. A003418.

Sequence in context: A090244 A210976 A258263 * A298637 A034867 A193790

Adjacent sequences:  A096177 A096178 A096179 * A096181 A096182 A096183

KEYWORD

nonn,tabl

AUTHOR

Matthew Vandermast, Jun 19 2004

STATUS

approved

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Last modified January 18 13:52 EST 2019. Contains 319271 sequences. (Running on oeis4.)