A050688 - OEIS

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

A050688

Numbers k such that A000422(k) is nonsquarefree.

2

8, 9, 15, 17, 18, 26, 27, 35, 36, 44, 45, 53, 54, 56, 62, 63, 71, 72, 80, 81, 89, 90, 98, 99, 107, 108, 109

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

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..27.

Patrick De Geest, Reversed Smarandache Concatenated Numbers, Prime factors from n down to 1

M. Fleuren, Factors and primes of Smarandache sequences.

M. Fleuren, Smarandache Factors and Reverse factors

Carlos Rivera, Puzzle 8. Primes by Listing, The Prime Puzzles & Problems Connection.

EXAMPLE

a(2)=9 because 987654321 = 3^2 * 17^2 * 379721.

CROSSREFS

Cf. A013929, A000422, A048288, A048342, A050687, A050675.

Sequence in context: A101765 A306490 A256351 * A134334 A351048 A292188

Adjacent sequences: A050685 A050686 A050687 * A050689 A050690 A050691

KEYWORD

nonn,base,hard

AUTHOR

Patrick De Geest, Aug 15 1999

EXTENSIONS

Definition corrected by Charles R Greathouse IV, Sep 20 2012

a(17)-a(24) and name corrected by Sean A. Irvine, Aug 17 2021

a(25)-a(27) from Daniel Suteu, Aug 18 2021

STATUS

approved