OFFSET
1,1
COMMENTS
Subsequence of A088483.
LINKS
Pierre CAMI, Table of n, a(n) for n = 1..10000
EXAMPLE
3 and 5 twin primes as 3*3+3-1=11 and 13, a(2)=3.
5 and 7 twin primes as 5*5+5-1=29 and 31, a(3)=5.
MATHEMATICA
Select[Transpose[Select[Partition[Prime[Range[21000]], 2, 1], #[[2]]-#[[1]] == 2&]][[1]], AllTrue[ #^2+#+{1, -1}, PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Nov 10 2014 *)
PROG
PFGW & SCRIPTIFY
SCRIPT
DIM n, 0
DIM m
DIM k, 0
DIMS ta
OPENFILEOUT myf, a(n).txt
OPENFILEIN maf, twin.txt
LABEL loop1
SET n, n+1
IF n>2999999 THEN END
GETNEXT m, maf
SETS ta, %d\,; n
PRP m^2+m-1, ta
IF ISPRP THEN GOTO a
GOTO loop1
LABEL a
PRP m^2+m+1, ta
IF ISPRP THEN GOTO b
GOTO loop1
LABEL b
WRITE myf, m
GOTO loop1
The file twin.txt has the first 3000000 of first of twin primes
(PFGW) ABC2 $a & $a+2 & $a^2+$a-1 & $a^2+$a+1
a: 1 to 3000000
Charles R Greathouse IV, Sep 10 2013
(PARI) is(n)=isprime(n)&&isprime(n+2)&&isprime(n^2+n-1)&&isprime(n^2+n+1) \\ Charles R Greathouse IV, Sep 10 2013
(Sage)
[x for x in primes_first_n(900) if x+2 in Primes() and x^2+x-1 in Primes() and x^2+x+1 in Primes()] #Tom Edgar, Sep 10 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Sep 10 2013
STATUS
approved