A121844 Excess of n^3 over previous prime.

1, 4, 3, 12, 5, 6, 3, 2, 3, 4, 5, 18, 3, 2, 3, 4, 5, 2, 7, 4, 9, 4, 17, 6, 3, 2, 9, 10, 7, 2, 19, 4, 3, 12, 7, 2, 3, 38, 3, 4, 11, 14, 25, 4, 9, 10, 5, 6, 9, 4, 5, 4, 7, 12, 15, 4, 9, 22, 17, 38, 7, 4, 5, 16, 5, 2, 9, 28, 11, 28, 17, 14, 3, 28, 9, 4, 5, 12, 3, 58, 5, 4, 11, 12, 13, 16, 21, 22, 7, 2, 7

Offset: 2

Author

Zak Seidov, Aug 29 2006

Keywords

• nonn

Examples

			a(5)=12 because 5^3=125 and previous prime is 113 hence a(5)=125-113=12
		

Crossrefs

Cf. A077037.

Programs

Mathematica

Table[n^3-Prime[PrimePi[n^3]],{n,2,100}]
#-NextPrime[#,-1]&/@((Range[2,100])^3) (* Harvey P. Dale, Apr 06 2013 *)

PARI

a(n) = n^3 - precprime(n^3 - 1) \\ Michel Marcus, Jun 03 2013