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A213815 Arithmetic mean of next a(n) successive nonnegative integers is prime.

%I A213815 #22 Feb 28 2025 12:06:42
%S A213815 5,1,3,5,7,5,7,9,3,5,7,5,11,1,11,9,7,1,3,5,7,21,3,17,11,9,3,1,19,21,3,
%T A213815 5,7,5,19,5,7,9,3,17,11,1,7,21,11,1,11,5,7,5,3,9,7,1,15,5,19,5,7,9,3,
%U A213815 5,19,5,11,9,15,25,7,5,7,9,11,1,11,5,7,1,3
%N A213815 Arithmetic mean of next a(n) successive nonnegative integers is prime.
%C A213815 Corresponding primes: A062044(n).
%H A213815 Robert Israel, <a href="/A213815/b213815.txt">Table of n, a(n) for n = 1..10000</a>
%e A213815 (0+1+2+3+4)/5 = 2 is prime, so a(1)=5,
%e A213815 then 5/1 = 5 is prime, so a(2)=1,
%e A213815 then (6+7+8)/3 = 7 is prime, so a(3)=3.
%p A213815 R:= 5: count:= 1: r:= 4:
%p A213815 for count from 2 to 100 do
%p A213815     s:= nextprime(r);
%p A213815     R:= R,2*(s-r)-1;
%p A213815     r:= 2*s - r - 1;
%p A213815 od:
%p A213815 R; # _Robert Israel_, Feb 28 2025
%Y A213815 Cf. A000040, A062044, A214362.
%K A213815 easy,nonn
%O A213815 1,1
%A A213815 _Alex Ratushnyak_, Jul 18 2012