A083574 - OEIS

A083574

Triangle: rows list the factors of composite odd n.

3, 3, 3, 5, 3, 7, 5, 5, 3, 3, 3, 3, 11, 5, 7, 3, 13, 3, 3, 5, 7, 7, 3, 17, 5, 11, 3, 19, 3, 3, 7, 5, 13, 3, 23, 3, 5, 5, 7, 11, 3, 3, 3, 3, 5, 17, 3, 29, 7, 13, 3, 31, 5, 19, 3, 3, 11, 3, 5, 7, 3, 37, 5, 23, 3, 3, 13, 7, 17, 11, 11, 3, 41, 5, 5, 5, 3, 43, 7

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OFFSET

1,1

COMMENTS

The primes make their first appearance according to their distribution after p=7.

LINKS

Table of n, a(n) for n=1..79.

EXAMPLE

The first odd composites are 9,15,21, with factors 3.3,3.5,3.7, so the sequence opens 3,3,3,5,3,7

MATHEMATICA

fcon[n_]:=Table[#[[1]], #[[2]]]&/@FactorInteger[n]; fcon/@Select[ Range[ 9, 151, 2], CompositeQ]//Flatten (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 20 2020 *)

CROSSREFS

Sequence in context: A070864 A321790 A076566 * A108025 A192451 A129856

Adjacent sequences: A083571 A083572 A083573 * A083575 A083576 A083577

KEYWORD

nonn,tabf

AUTHOR

Jon Perry, Jun 13 2003

EXTENSIONS

Corrected and extended by Harvey P. Dale, Aug 20 2020

STATUS

approved