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

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, 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, 5, 19, 5, 11, 9, 15, 25, 7, 5, 7, 9, 11, 1, 11, 5, 7, 1, 3

Offset: 1

Author

Alex Ratushnyak, Jul 18 2012

Keywords

• easy
• nonn

Comments

Corresponding primes: A062044(n).

Examples

			(0+1+2+3+4)/5 = 2 is prime, so a(1)=5,
then 5/1 = 5 is prime, so a(2)=1,
then (6+7+8)/3 = 7 is prime, so a(3)=3.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000040, A062044, A214362.

Programs

Maple

R:= 5: count:= 1: r:= 4:
for count from 2 to 100 do
    s:= nextprime(r);
    R:= R,2*(s-r)-1;
    r:= 2*s - r - 1;
od:
R; # Robert Israel, Feb 28 2025