A060325 a(n) = n-th prime prime(n) subtracted from sum of all composites between prime(n) and prime(n-1).

-3, -1, -1, 16, -1, 28, -1, 40, 101, -1, 133, 76, -1, 88, 197, 221, -1, 253, 136, -1, 301, 160, 341, 554, 196, -1, 208, -1, 220, 1433, 256, 533, -1, 1147, -1, 613, 637, 328, 677, 701, -1, 1483, -1, 388, -1, 2044, 2164, 448, -1, 460, 941, -1, 1963, 1013, 1037, 1061, -1, 1093, 556, -1, 2299, 3593, 616, -1, 628, 3881

Offset: 2

Author

Jason Earls, Apr 10 2001

Keywords

• easy
• sign

Examples

			a(2) = 0 - 3 = -3. a(5) = (8+9+10) - 11 = 16.
		

Links

• James Spahlinger, Table of n, a(n) for n = 2..1000

Programs

Mathematica

a[n_] := Total@Range[Prime[n - 1] + 1, Prime[n] - 1] - Prime[n]; Array[a,50,2] (* James Spahlinger, Feb 20 2016 *)

Formula

a(n) = A054265(n-1) - A065091(n-1). - James Spahlinger, Feb 20 2016

Extensions

Corrected and extended by Larry Reeves (larryr(AT)acm.org), Apr 20 2001