A147861 - OEIS

A147861

Triangle read by rows: T(n,k)=min(k, n/k) if k divides n, T(n,k)=0 otherwise (n >=1, 1<=k<=n).

1, 1, 1, 1, 0, 1, 1, 2, 0, 1, 1, 0, 0, 0, 1, 1, 2, 2, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 2, 0, 2, 0, 0, 0, 1, 1, 0, 3, 0, 0, 0, 0, 0, 1, 1, 2, 0, 0, 2, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 3, 3, 0, 2, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1

(list; table; graph; refs; listen; history; text; internal format)

OFFSET

1,8

LINKS

Table of n, a(n) for n=1..91.

Omar E. Pol, Determinacion geometrica de los numeros primos y perfectos [From Omar E. Pol, Jul 20 2009]

Omar E. Pol, Illustration: Divisors and pi(x) [From Omar E. Pol, Jul 20 2009]

EXAMPLE

Triangle begins:

1,1;

1,0,1;

1,2,0,1;

1,0,0,0,1;

1,2,2,0,0,1;

1,0,0,0,0,0,1;

1,2,0,2,0,0,0,1;

1,0,3,0,0,0,0,0,1;

1,2,0,0,2,0,0,0,0,1;

1,0,0,0,0,0,0,0,0,0,1;

1,2,3,3,0,2,0,0,0,0,0,1;

1,0,0,0,0,0,0,0,0,0,0,0,1;

1,2,0,0,0,0,2,0,0,0,0,0,0,1;

1,0,3,0,3,0,0,0,0,0,0,0,0,0,1;

1,2,0,4,0,0,0,2,0,0,0,0,0,0,0,1;

1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1;

1,2,3,0,0,3,0,0,2,0,0,0,0,0,0,0,0,1;

1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1;

1,2,0,4,4,0,0,0,0,2,0,0,0,0,0,0,0,0,0,1;

1,0,3,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,1;

1,2,0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,1;

1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1;

1,2,3,4,0,4,0,3,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0,1;

1,0,0,0,5,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1;

1,2,0,0,0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0,0,1;

1,0,3,0,0,0,0,0,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1;

1,2,0,4,0,0,4,0,0,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0,0,0,1;

1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1;

1,2,3,0,5,5,0,0,0,3,0,0,0,0,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1;

...

Row sums: A117004.

CROSSREFS

Cf. A000005, A008578, A027750, A051731, A117004, A127093, A161345, A161424, A161835, A162526, A162527, A162528, A162529, A162530, A162531, A162532. [From Omar E. Pol, Jul 20 2009]

Sequence in context: A064874 A286563 A216282 * A167271 A156348 A306437

Adjacent sequences: A147858 A147859 A147860 * A147862 A147863 A147864

KEYWORD

nonn,tabl

AUTHOR

Omar E. Pol, Nov 16 2008, Jul 20 2009

EXTENSIONS

Submitted without a definition, which was supplied by Jon E. Schoenfield, Dec 13 2008

STATUS

approved