%I
%S 8,12,24,36,60,84,120,144,204,216,276,300,360,384,396,456,480,540,564,
%T 624,696,840,864,924,1044,1140,1200,1236,1284,1320,1620,1644,1656,
%U 1716,1764,2040,2064,2100,2124,2184,2304,2460,2556,2580,2604,2640,2856,2904
%N Sum of twin prime pairs.
%C (p^q)+(q^p) calculated modulo pq, where (p,q) is the nth twin prime pair. Example: (599^601)+(601^599) == 1200 mod (599*601).  _Sam Alexander_, Nov 14 2003
%C El'hakk makes the following claim (without any proof): (q^p)+(p^q) = 2*cosh(q arctanh( sqrt( 1((2/p)^2) ) )) + 2cosh(p arctanh( sqrt( 1((2/q)^2) ) )) mod p*q  _Sam Alexander_, Nov 14 2003
%C Also: Numbers N such that N/21 and N/2+1 both are prime.  _M. F. Hasler_, Jan 03 2013
%C Excluding the first term, all remaining terms have digital root 3, 6 or 9.  _J. W. Helkenberg_, Jul 24 2013
%H Reinhard Zumkeller, <a href="/A054735/b054735.txt">Table of n, a(n) for n = 1..10000</a>
%H El'hakk, <a href="http://web.archive.org/web/http://www.geocities.com/timeparadox/elhakk.htm">Page of the time traveler</a> [Archived copy on web.archive.org, as of Oct 28 2009.]
%F a(n) = 2*A014574(n) = 4*A040040(n) = A111046(n)/2.
%e a(3)=24 because the twin primes 11 and 13 add to 24.
%p ZL:=[]:for p from 1 to 1451 do if (isprime(p) and isprime(p+2)) then ZL:=[op(ZL),p+(p+2)]; fi; od; print(ZL); # _Zerinvary Lajos_, Mar 07 2007
%p A054735 := proc(n)
%p 2*A001359(n)+2;
%p end proc: # _R. J. Mathar_, Jan 06 2013
%t Select[Table[Prime[n] + 1, {n, 230}], PrimeQ[ # + 1] &] *2 (* _Ray Chandler_, Oct 12 2005 *)
%o (PARI) is_A054735(n)={!bittet(n,0)&&isprime(n\21)&&isprime(n\2+1)} \\ _M. F. Hasler_, Jan 03 2013
%o (PARI) pp=1;forprime(p=1,1482, if( p==pp+2, print1(p+pp,", ")); pp=p) \\ Following a suggestion by _R. J. Cano_, Jan 05 2013
%o (Haskell)
%o a054735 = (+ 2) . (* 2) . a001359  _Reinhard Zumkeller_, Feb 10 2015
%Y Cf. A001359, A006512, A014574, A040040, A111046.
%K easy,nonn
%O 1,1
%A _Enoch Haga_, Apr 22 2000
%E Additional comments from _Ray Chandler_, Nov 16 2003
%E Broken link fixed by _M. F. Hasler_, Jan 03 2013
