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A161749 Smallest distinct primes, if they exist, in x^n - y^(n-2). 0
3, 2, 7, 5, 127, 3299, 1967249047, 8191, 30450469261 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

For even n > 4 = 2m, x^2m - y^(2m-2) = (x^m)^2 - y^((m-1))^2 is divisible by

x^m - y^(m-1) which is not prime. This accounts for the phrase "if they exist"

in the definition.

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: A155046 A033318 A093780 * A101307 A096899 A154448

Adjacent sequences:  A161746 A161747 A161748 * A161750 A161751 A161752

KEYWORD

nonn,uned

AUTHOR

Cino Hilliard (hillcino368(AT)hotmail.com), Jun 17 2009

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Last modified February 14 16:24 EST 2012. Contains 205635 sequences.