BBC Russian

Svoboda | Graniru | BBC Russia | Golosameriki | Facebook

The OEIS is supported by the many generous donors to the OEIS Foundation.

A258569

Smallest prime factors of 4-full numbers, a(1)=1.

1, 2, 2, 2, 3, 2, 3, 2, 2, 5, 3, 2, 2, 2, 3, 7, 2, 5, 2, 2, 2, 3, 2, 2, 2, 2, 2, 11, 2, 5, 2, 7, 3, 2, 2, 2, 13, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 2, 2, 2, 5, 2, 2, 17, 2, 2, 2, 7, 2, 19, 2, 2, 3, 2, 2, 11, 2, 3, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 23, 2, 2, 2, 2 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,2`
	LINKS	`Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 (some terms corrected by Georg Fischer)`
	FORMULA	`a(n) = A020639(A036967(n));` `a(A258601(n)) = A000040(n) and a(m) != A000040(n) for m < A258601(n).`
	MATHEMATICA	`Reap[Sow[1]; Do[f = FactorInteger[k]; If[Min[f[[All, 2]]] >= 4, Sow[f[[1, 1]]]], {k, 2, 10^6}]][[2, 1]] (* Jean-François Alcover, Sep 29 2020 *)`
	PROG	`(Haskell)` `a258569 = a020639 . a036967`
	CROSSREFS	`Cf. A036967, A020639, A258601, A258567, A258568, A258570, A258571.` `Sequence in context: A024676 A093429 A089842 * A091322 A252229 A318490` `Adjacent sequences: A258566 A258567 A258568 * A258570 A258571 A258572`
	KEYWORD	`nonn`
	AUTHOR	`Reinhard Zumkeller, Jun 06 2015`
	STATUS	`approved`

License Agreements, Terms of Use, Privacy Policy. .

Last modified August 6 10:29 EDT 2024. Contains 374969 sequences. (Running on oeis4.)