A235267 - OEIS

%I #10 Jan 17 2014 14:38:57

%S 3,5,33,35,43,69,86,106,108,116,124,127,171,174,182,200,201,238,255,

%T 256,270,271,277,294,310,318,323,332,356,384,388,390,392,397,398,402,

%U 409,469,494,495,520,542,551,562,572,582,606,632,633,645,649,652,671,672

%N Places n such that 1 + q!/p! is prime, where p = prime(n) and q = prime(n + 1).

%H K. D. Bajpai, <a href="/A235267/b235267.txt">Table of n, a(n) for n = 1..1510</a>

%e 3 is in the sequence because (prime(3)! + prime(4)!)/prime(3)! =  (5! + 7!)/5! = (120 + 5040)/120 =  43 which is prime.

%p isA235267 := proc(n)

%p     local p,q ;

%p     p := ithprime(n) ;

%p     q := nextprime(p) ;

%p     if isprime(1+q!/p!) then

%p         true;

%p     else

%p         false;

%p     end if;

%p end proc:

%p for n from 1 do

%p     if isA235267(n) then

%p         print(n) ;

%p     end if;

%p end do:

%Y Cf. A000040, A100858.

%K nonn

%O 1,1

%A _K. D. Bajpai_, Jan 05 2014