login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A171435 Product of odd prime factors < n, with multiplicity. 2
1, 1, 1, 1, 1, 3, 1, 1, 9, 5, 1, 3, 1, 7, 15, 1, 1, 9, 1, 5, 21, 11, 1, 3, 25, 13, 27, 7, 1, 15, 1, 1, 33, 17, 35, 9, 1, 19, 39, 5, 1, 21, 1, 11, 45, 23, 1, 3, 49, 25, 51, 13, 1, 27, 55, 7, 57, 29, 1, 15, 1, 31, 63, 1, 65, 33, 1, 17, 69, 35, 1, 9, 1, 37, 75, 19, 77, 39, 1, 5, 81, 41, 1, 21, 85 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

COMMENTS

In this sequence p < n, but p^k with k>=2 may be equal to n.

a(n) = 1 iff n = 2^k, k >= 0 or n is prime;

1 < a(n) < n iff n is even composite and not a power of 2;

a(n) = n iff n is nonprime (unit or composite) odd.

LINKS

Daniel Forgues, Table of n, a(n) for n=1..100000

CROSSREFS

Cf. A171487, A000265, A010051.

Sequence in context: A142992 A145905 A336859 * A144183 A050153 A294950

Adjacent sequences:  A171432 A171433 A171434 * A171436 A171437 A171438

KEYWORD

nonn

AUTHOR

Daniel Forgues, Dec 09 2009

EXTENSIONS

Edited by Daniel Forgues, Dec 10 2009

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 11 00:03 EDT 2021. Contains 342877 sequences. (Running on oeis4.)