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!)
A023583 Greatest prime divisor of 2*prime(n)-1. 1
3, 5, 3, 13, 7, 5, 11, 37, 5, 19, 61, 73, 3, 17, 31, 7, 13, 11, 19, 47, 29, 157, 11, 59, 193, 67, 41, 71, 31, 5, 23, 29, 13, 277, 11, 43, 313, 13, 37, 23, 17, 19, 127, 11, 131, 397, 421, 89, 151, 457, 31, 53, 37, 167, 19, 7, 179, 541, 79, 17, 113, 13, 613, 23, 5 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) = 2*prime(n)-1 if n is in A137288. - Robert Israel, May 19 2020

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A006530(A076274(n+1)). - Bernard Schott, May 20 2020

MAPLE

f:= n -> max(numtheory:-factorset(2*ithprime(n)-1)):

map(f, [$1..100]); # Robert Israel, May 19 2020

CROSSREFS

Cf. A006530, A076274, A137288.

Sequence in context: A023585 A089948 A336806 * A266603 A121278 A023587

Adjacent sequences:  A023580 A023581 A023582 * A023584 A023585 A023586

KEYWORD

nonn

AUTHOR

Clark Kimberling

EXTENSIONS

Name edited by Robert Israel, May 19 2020

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 June 21 18:42 EDT 2021. Contains 345365 sequences. (Running on oeis4.)