A218908 - OEIS

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

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A218908

Primes p such that k*p is greater than the greatest prime factor of p^k - 1 and p^k + 1 for k = 1 to k = 4.

3373, 41893, 62497, 105557, 165701, 201577, 208877, 239803, 302399, 333107

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

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..10.

EXAMPLE

The greatest factors of 3373^4 - 1 , 3373^6 - 1 and 3373^8 - 1 are respectively: 317, 6379, 7369.

PROG

(PARI) forprime(h=3, 400000, f=h^3-1; g=h^3+1; k=vecmax(factor(f)[, 1]~); l=vecmax(factor(g)[, 1]~); m=h^4-1; n=h^4+1; o=vecmax(factor(m)[, 1]~); p=vecmax(factor(n)[, 1]~); if(3*h>k && 3*h>l && 4*h>o && 4*h>p, print1(h, ", ")))

CROSSREFS

Cf. A218833, A218834, A218863.

Sequence in context: A031626 A117921 A052357 * A164521 A251153 A305500

Adjacent sequences: A218905 A218906 A218907 * A218909 A218910 A218911

KEYWORD

nonn

AUTHOR

Robin Garcia, Nov 08 2012

STATUS

approved