1,1

Conjecture: If the condition holds, prime(n-1) and prime(n) are twin primes of

the form 10k+9 and 10k1+1, i.e. the last digits of the twin prime pairs are 9

and 1. The 9 ending is evident in this sequence. The table of the first 101

terms was computed using Zak Seidov's table.

Cino Hilliard, List of n, a(n) for n=1..101

S. M. Ruiz, Integer then equal.

Zak Seidov, A158470 first 101 terms.

Prime(n) is the nth prime number.

For n = 11, prime(11-1)=29,29+7=36;prime(11+1)=37,37-1=36. So 29 is the first

entry in the sequence.

(PARI) \\Copy and paste the Zak's file to zaklist.txt and edit to a straight

\\list with CR after each entry. Start a new Pari sesion then \r zakilist.txt

integerequal(a, b) =

{

local(x, p1, p2);

for(j=1, 101,

x=eval(concat("%", j)); p1=prime2(x-1);

if(issquare(p1+a),

p2=prime2(x+1); if((p1+a)==(p2-b),

print1(p1", ")

)

prime2(n) = \\the nth prime using c:\sieve\prime.exe calling 8byte binary

\\g:\sievedata\prime2-1trill.bin" 300 gig file of primes <10^12

{

local(x, s);

s=concat("c:/sieve/prime ", Str(n));

s=concat(s, " > temp.txt");

\\Must save to a temp file for correct output

system(s);

return(read("temp.txt"))

}

)

)

}

Sequence in context: A023948 A020974 A167740 this_sequence A020766 A069295 A103723

Adjacent sequences: A158526 A158527 A158528 this_sequence A158530 A158531 A158532

nonn

Cino Hilliard (hillcino368(AT)hotmail.com), Mar 20 2009

Edited by N. J. A. Sloane Aug 31 2009 (rephrased definition, corrected offset).