cp's OEIS Frontend

A281318 Number of consecutive nonprime numbers following Euclid numbers A006862.

%I A281318 #17 Jan 30 2017 18:46:02
%S A281318 1,3,5,11,21,15,17,21,35,59,65,59,69,45,105,57,59,107,87,101,77,149,
%T A281318 195,99,101,231,221,125,221,189,161,227,641,237,155,165,437,237,197,
%U A281318 189,197,381,231,749,311,771,605,311,381,291,441,329,281,275,269,399
%N A281318 Number of consecutive nonprime numbers following Euclid numbers A006862.
%C A281318 For n > 1, a(n) >= prime(n), with equality if and only if A006862(n) + prime(n) + 1 is prime.  Equality occurs for n=2, 3, 7, 17.  Are there any others? - _Robert Israel_, Jan 30 2017
%H A281318 Robert Israel, <a href="/A281318/b281318.txt">Table of n, a(n) for n = 1..469</a>
%F A281318 NextPrime[pn# + 1] - pn# - 1
%e A281318 a(3) = 5 because primorial p_3# = 5# = 2*3*5 = 30 thus 31 is the third Euclid number, and there are 5 consecutive nonprime numbers {32,33,34,35,36} between 31 and the next prime, 37. - _Michael De Vlieger_, Jan 20 2017
%p A281318 p:= 0: pn:= 1:
%p A281318 for n from 1 to 100 do
%p A281318   p:= nextprime(p);
%p A281318 pn:= pn*p;
%p A281318 A[n]:= nextprime(pn+1)-(pn+2);
%p A281318 od:
%p A281318 seq(A[n],n=1..100); # _Robert Israel_, Jan 30 2017
%t A281318 Table[Function[p, NextPrime@ p - p - 1][Times @@ Prime@ Range@ n + 1], {n, 56}] (* _Michael De Vlieger_, Jan 20 2017 *)
%Y A281318 Cf. A006862, A002110.
%K A281318 nonn
%O A281318 1,2
%A A281318 _Olivier Bélot_, Jan 20 2017
%E A281318 More terms from _Michael De Vlieger_, Jan 20 2017