OFFSET
1,1
COMMENTS
All terms == 15 or 39 (mod 60). - Robert Israel, Nov 30 2025
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
FORMULA
a(n) = A114335(n)^2 - 1. - Alois P. Heinz, Nov 30 2025
EXAMPLE
3*5 = 15+-2 -> primes, 9*11 = 99+-2 -> primes.
MAPLE
R:= NULL: count:= 0:
for i from 3 by 2 while count < 100 do
v:= i*(i+2);
if isprime(v-2) and isprime(v+2) then count:= count+1; R:= R, v fi
od:
R; # Robert Israel, Nov 30 2025
MATHEMATICA
f[n_]:=n*(n+2); Select[Table[f[n], {n, 1, 7!, 2}], PrimeQ[ #-2]&&PrimeQ[ #+2]&]
Select[Times@@@Partition[Range[1, 2001, 2], 2, 1], And@@PrimeQ[#+{2, -2}]&] (* Harvey P. Dale, Dec 14 2012 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Vladimir Joseph Stephan Orlovsky, Mar 17 2010
STATUS
approved