OFFSET
1,21
COMMENTS
Conjecture: a(n) is nonzero for any n > 35.
Clearly this conjecture implies the twin prime conjecture.
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..500 (* First 200 terms from Zhi-Wei Sun *)
EXAMPLE
a(1) = 1 since 2*(1 + 1) - 1 = 3 and 2*(1 + 1) + 1 =5 are twin primes.
MATHEMATICA
a[n_]:=a[n]=Det[Table[If[PrimeQ[2(i+j)-1]&&PrimeQ[2(i+j)+1], 1, 0], {i, 1, n}, {j, 1, n}]]
Table[a[n], {n, 1, 20}]
Table[Det[Table[If[AllTrue[2(i+j)+{1, -1}, PrimeQ], 1, 0], {i, k}, {j, k}]], {k, 60}] (* The program uses the AllTrue function from Mathematica version 10 *) (* Harvey P. Dale, Sep 21 2019 *)
CROSSREFS
KEYWORD
sign
AUTHOR
Zhi-Wei Sun, Aug 27 2013
STATUS
approved