A109709 - OEIS

A109709

Triangle in which n-th row gives the prime factors of the n-th composite number with repetition.

2, 2, 2, 3, 2, 2, 2, 3, 3, 2, 5, 2, 2, 3, 2, 7, 3, 5, 2, 2, 2, 2, 2, 3, 3, 2, 2, 5, 3, 7, 2, 11, 2, 2, 2, 3, 5, 5, 2, 13, 3, 3, 3, 2, 2, 7, 2, 3, 5, 2, 2, 2, 2, 2, 3, 11, 2, 17, 5, 7, 2, 2, 3, 3, 2, 19, 3, 13, 2, 2, 2, 5, 2, 3, 7, 2, 2, 11, 3, 3, 5, 2, 23, 2, 2, 2, 2, 3, 7, 7, 2, 5, 5, 3, 17, 2, 2, 13, 2, 3, 3, 3

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

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..102.

EXAMPLE

Irregular triangle begins:

2, 2;

2, 3;

2, 2, 2;

3, 3;

2, 5;

...

MATHEMATICA

fn[{a_, b_}]:=Table[a, b]; Flatten[Table[fn/@FactorInteger[ ResourceFunction["Composite"][n]], {n, 37}]] (* James C. McMahon, Mar 29 2024 *)

CROSSREFS

Column k=1 gives A056608.

Last terms in rows give A052369.

Row lengths give A062502(n+1).

Cf. A002808, A027746.

Sequence in context: A065569 A262941 A127656 * A125604 A216685 A331853

Adjacent sequences: A109706 A109707 A109708 * A109710 A109711 A109712

KEYWORD

nonn,tabf

AUTHOR

Lior Manor, Aug 08 2005

STATUS

approved