A256736 Number of composites lying between successive pairs of primes, beginning with pair (3,5). Bisection of A046933.
1, 3, 3, 3, 1, 3, 3, 5, 5, 1, 3, 7, 1, 1, 13, 5, 9, 5, 3, 5, 9, 3, 11, 3, 3, 1, 5, 5, 5, 1, 13, 1, 13, 9, 3, 7, 5, 5, 3, 9, 9, 5, 5, 3, 3, 7, 7, 5, 1, 5, 5, 1, 9, 5, 5, 3, 11, 1, 5, 1, 3, 7, 7, 7, 5, 7, 3, 3, 9, 1, 1, 1, 13, 1, 13, 1, 19, 7, 7, 5, 13, 5, 7, 11
Offset: 1
Keywords
Examples
[3,5] contains 4, so a(1)=4. [7,11] contains 8,9,10, so a(2)=3. For the third term in the sequence, use prime pair [13,17]. There are three composites between 13 and 17, thus the third term = 3.
Links
- Jinyuan Wang, Table of n, a(n) for n = 1..1000
Programs
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Mathematica
Table[Prime[n + 1] - Prime[n] - 1, {n, 2, 100, 2}] (* Hartmut F. W. Hoft, Apr 24 2015 *) -
PARI
a(n) = prime(2*n+1)-prime(2*n)-1; \\ Jinyuan Wang, Jul 09 2020
Extensions
Corrected and extended by Hartmut F. W. Hoft, Apr 24 2015
More terms from Robert G. Wilson v, May 03 2015