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!)
A085378 Difference between primes p and the largest prime divisor of p-1. 1
3, 4, 6, 10, 15, 16, 12, 22, 26, 34, 36, 36, 24, 40, 30, 56, 56, 64, 70, 66, 42, 78, 94, 96, 86, 54, 106, 106, 120, 118, 120, 116, 112, 146, 144, 160, 84, 130, 90, 176, 172, 190, 190, 188, 204, 186, 114, 210, 204, 222, 236, 246, 255, 132, 202, 266, 254, 274, 236 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

COMMENTS

This sequence contains only one prime number, the 3.

LINKS

Table of n, a(n) for n=3..61.

EXAMPLE

For prime 107 we have 107 - 53 = 54.

MAPLE

A085378 := proc(n)

    ithprime(n)-A023503(n) ;

end proc:

seq( A085378(n), n=3..80) ; # R. J. Mathar, Sep 07 2016

MATHEMATICA

#-FactorInteger[#-1][[-1, 1]]&/@Prime[Range[3, 70]] (* Harvey P. Dale, Jan 04 2012 *)

PROG

(PARI) cminuspm1(n) = \ prime - maxprime of prime-1 { forprime(x=5, n, forstep(p=x, 2, -1, if(isprime(p) & (x-1)%p==0, print1(x-p, ", "); break); ) ) }

CROSSREFS

Sequence in context: A167410 A302340 A310003 * A255879 A171096 A125869

Adjacent sequences:  A085375 A085376 A085377 * A085379 A085380 A085381

KEYWORD

easy,nonn

AUTHOR

Cino Hilliard, Aug 12 2003

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 22 12:08 EDT 2021. Contains 343177 sequences. (Running on oeis4.)