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A161747 Primes of the form x^5-y^4, where x,y >= 1. 0
31, 227, 1051, 3109, 7151, 15511, 18127, 30367, 32143, 32687, 144719, 151051, 165311, 186343, 234191, 302399, 369997, 371281, 374239, 407503, 454303, 509263, 531263, 537743, 759359, 1053007, 1088081, 1182287, 1185601, 1354321, 1381441 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

If a prime has multiple representations of the format, it is entered only once.

LINKS

Table of n, a(n) for n=1..31.

FORMULA

If x^5-y^4 is prime for integers x,y list without duplicates.

EXAMPLE

2^5 - 1^4 = 31.

PROG

(PARI) diffpowers(n, m) =

{

local(a, c=0, c2=0, j, k, y);

a=vector(floor(n^2/log(n^2)));

for(j=1, n,

for(k=1, n,

y=j^m-k^(m-1);

if(ispseudoprime(y),

c++;

\\ print(j", "k", "y);

a[c]=y;

);

);

);

a=vecsort(a);

for(j=2, length(a),

if(a[j]!=a[j-1]&&a[j]!=0,

c2++;

print1(a[j]", ");

if(c2>100, break);

);

);

}

CROSSREFS

Sequence in context: A075931 A142440 A075932 * A059899 A140846 A082544

Adjacent sequences:  A161744 A161745 A161746 * A161748 A161749 A161750

KEYWORD

nonn

AUTHOR

Cino Hilliard, Jun 17 2009

STATUS

approved

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Last modified September 30 02:48 EDT 2020. Contains 337432 sequences. (Running on oeis4.)