A258972 Number of other odd numbers between the twin primes, with a(1) = 1.

1, 1, 1, 4, 4, 7, 4, 13, 1, 13, 4, 13, 4, 1, 13, 4, 13, 4, 13, 16, 34, 4, 13, 28, 22, 13, 7, 10, 7, 73, 4, 1, 13, 10, 67, 4, 7, 4, 13, 28, 37, 22, 4, 4, 7, 52, 10, 13, 1, 58, 4, 22, 13, 10, 31, 40, 1, 25, 7, 22, 13, 25, 1, 10, 7, 4, 46, 13, 19, 13, 19, 82, 19, 31, 13, 10, 7, 28, 4, 82, 13, 58, 22, 40, 1, 19, 13, 13, 4, 7, 34, 1

Offset: 1

Author

Omar E. Pol, Jun 15 2015

Keywords

• nonn

Comments

Bisection of A256262.

Examples

			--------------------------------------------
.         Other            Twin
.      odd numbers        primes
n        A255763         A001097       a(n)
--------------------------------------------
1           1            3, 5, 7        1
2           9             11, 13        1
3          15             17, 19        1
4    21, 23, 25, 27       29, 31        4
5    33, 35, 37, 39       41, 43        4
...
For n = 5, between the successive pairs of twin primes [29, 31] and [41, 43] there are four odd numbers that are not twin primes: 33, 35, 37, 39, so a(5) = 4.
		

Crossrefs

Cf. A001359, A001097, A006512, A255763, A256262.

Formula

a(n) = abs((A001359(n+1) - A001359(n))/2 - 2).

a(n) = abs((A006512(n+1) - A006512(n))/2 - 2).