The On-Line Encyclopedia of Integer Sequences (OEIS)

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Primes in the progression (n!- m)/m where n advances by 1 and m resets to 1 upon each prime occurrence.
(history; published version)

#3 by N. J. A. Sloane at Tue Oct 01 17:57:46 EDT 2013

AUTHOR

_Cino Hilliard (hillcino368(AT)gmail.com), _, Dec 05 2003

Discussion

Tue Oct 01

17:57

OEIS Server: https://oeis.org/edit/global/1955

#2 by N. J. A. Sloane at Wed Dec 06 03:00:00 EST 2006

KEYWORD

base,easy,nonn,new

AUTHOR

Cino Hilliard (hillcino368(AT)hotmailgmail.com), Dec 05 2003

#1 by N. J. A. Sloane at Thu Feb 19 03:00:00 EST 2004

NAME

Primes in the progression (n!- m)/m where n advances by 1 and m resets to 1 upon each prime occurrence.

DATA

5, 23, 59, 719, 5039, 10079, 181439, 907199, 7983359, 479001599, 622702079, 87178291199, 326918591999, 6974263295999, 59281238015999, 1600593426431999, 15205637551103999, 405483668029439999, 5676771352412159999

OFFSET

1,1

EXAMPLE

n=5,m=1 (5!-1)/1 = 119=7*17 not prime m advances to 2.

n=5,m=2 (5!-2)/2 = 118/2 = 59 prime keep it.

PROG

(PARI) nfactm2d2(n, m) = { for(x=1, n, for(k=1, m, y=floor((x!- k)/k); if(isprime(y), print1(y", "); break) ) ) }

KEYWORD

base,easy,nonn

AUTHOR

Cino Hilliard (hillcino368(AT)hotmail.com), Dec 05 2003

STATUS

approved